For the language phenomenon where the English language is heavily influenced by another language, a portmanteau term combined from the name of two languages is used. In your specific example, it is Swenglish (also called Swinglish, Swedlish and Sweglish):
Swenglish is a colloquial term referring to the English language heavily influenced by Swedish in terms of vocabulary, grammar, or pronunciation. - Wikipedia
As with most non-native speech, native Swedish speakers may pick the wrong word when speaking English based on what sounds right in their own language. While Swedish and English share many words, both from their Germanic origins, and from later French and Latin influence, there are several Swedish-English false friends, such as nacke (similar to English "neck") meaning 'nape, back of the neck', and eventuellt (similar to "eventually") meaning 'possibly'.
Note: Spanglish (combining Spanish and English) is possibly the most popular one but it also has an extended sense which can include hybrid languages, pidgins and creoles based on the extensive interactions between Spanish and English. There are also other colloquial portmanteau terms (with various alternative forms) like Chinglish (Chinese and English), Danglish (Danish and English), Dunglish (Dutch and English), Denglisch/Denglish/Germanglish (Deutsch/German and English) etc.
In your examples, you are specifically asking for the foreign language influence on vocabulary. In linguistics, the general term for the word substitution/selection errors you've provided is a lexical selection error. It can occur within the same language or between two languages (within bilingual lexical access by bilinguals).
Several forms of speech error involve problems with selecting the correct word (lexical selection). A simple kind of lexical selection error is semantic substitution (the correct word is replaced by a word of similar meaning, e.g., "Where is my tennis bat?" instead of "Where is my tennis racquet?"). In 99% of cases, the substituted word is of the same form class as the correct word (e.g., nouns substitute for nouns). Verbs are much less likely than nouns, adjectives, or adverbs to undergo semantic substitution (Hotopf, 1980).
Cognitive Psychology: A Student's Handbook by Michael W. Eysenck, Mark T. Keane
In your first two examples, the word formation is called a blend and the process is called blending. Blending can occur as a speech error in lexical selection by erronously blending two words (usually with semantic similarity) within the same language or two words from different languages in bilinguals. Although it can be called a portmanteau too, there is a distinction between a portmanteau and a blend in linguistics; and the term blending is used in lexical errors of this type.
In linguistics, a blend (sometimes called blend word, lexical blend, portmanteau or portmanteau word) is a word formed from parts of two or more other words. At least one of these parts is not a morph (the realization of a morpheme) but instead a mere splinter, a fragment that is normally meaningless - Blend word / Wikipedia
In linguistics, a blend is an amalgamation or fusion of independent lexemes, while a portmanteau or portmanteau morph is a single morph that is analyzed as representing two (or more) underlying morphemes. - Portmanteau morph / Wikipedia
Blend word article in Wikipedia also includes the explanation below for the lexical selection error, citing the book "An Introduction to Language (8th ed.)" by Fromkin, Victoria; Rodman, R.; Hyams, Nina (2007):
Blending may occur with an error in lexical selection, the process by which a speaker uses his semantic knowledge to choose words. Lewis Carroll's explanation, which gave rise to the use of 'portmanteau' for such combinations, was:
Humpty Dumpty's theory, of two meanings packed into one word like
a portmanteau, seems to me the right explanation for all. For instance, take the two words "fuming" and "furious." Make up your mind that you will say both words ... you will say "frumious."
The errors are based on similarity of meanings, rather than phonological similarities, and the morphemes or phonemes stay in the same position within the syllable.
The book Handbook of Bilingualism: Psycholinguistic Approaches (edited by Judith F. Kroll, Annette M. B. De Groot) provides an in-depth analysis on bilingual lexical selection processes and errors. Here are the relevant excerpts where word intrusions, semantic substitutions, blends, code-switching, ugly sisters/blocking words in bilingual access are explained:
First, bilinguals speaking in their L2 may accidentally insert words from their L1. In line with the above argument, Poulisse and Bongaerts (1994) related these "performance switches" to semantic substitutions in L1. Even blends of words from two languages have been observed (e.g., "springling" from English spring and German Frühling).
Access is complex in the sense that the preverbal message contains all the relevant information, including the intended language. During lexical access, not only the sought-for word, but also many semantically related words become activated, including words in the nonintended language. Lexical selection is a simple, local process that is only based on the activation levels of words.
Interestingly, as argued by the authors, this model
also provides a satisfactory account of three phenomena pertinent to any model of bilingual access:
the ability to separate languages, code switching
(rapid switching between the two languages), and
accidental intrusions from the nonintended language. The ability to separate languages follows
from the use of a language cue at the conceptual
level. For example, when the speaker intends to
use L2, L2 words receive more activation than the
corresponding L1 words. Code switching can be
fast because there is no active inhibition of words
in one of the two languages, and intrusions may
either result from the failure to use the correct
language cue or from incidental cases in which the
word in the unintended language reaches a higher
activation level than the intended word (e.g., because of priming effects).
A nice illustration of this assumed automaticity is the ‘‘ugly sister’’ phenomenon that speakers
in a tip-of-the-tongue state may experience (Reason & Lucas, 1984). The attempt to find the correct word sometimes leads to the activation of an
incorrect word (the ugly sister) that is immediately
rejected by the speaker. However, each new attempt to retrieve the correct word only leads to the
reactivation of the ugly sister, which for that reason
is also referred to as a blocking word. This phenomenon is exactly what may be expected if lexical
selection is an automatic process only based on
activation levels: Given a certain input (the preverbal message) and the current levels of activation
of the lexical representations, the same output will
be produced time and time again.
There are two other broad linguistics phenomena that can play a role in foreign-language influence; although they are very comprehensive and cover many factors:
- The first one is crosslinguistic influence where speakers transfer aspects from their native language (or another language they know) when using a second or foreign language. This can result in production errors involving substitutions as it influences vocabulary as well.
Crosslinguistic influence (CLI) refers to the different ways in which one language can affect another within an individual speaker. It typically involves two languages that can affect one another in a bilingual speaker.
Substitution is when the L1 speaker takes a structure or word from their native language and replaces it within the L2. Odlin (1989) shows a sentence from a Swedish learner of English in the following sentence.
- Swedish Structure on English:
• But sometimes I must go bort.
Here the Swedish word bort has replaced its English equivalent away.
- Crosslinguistic influence - Wikipedia
- The second one is language attrition where a native speaker loses fluency in their native language as a result of increased use of a foreign language. As the OP mentioned: "a native speaker of English who, for example, spent a lot of time in Sweden to the point that it affects their phrasing in English". In this process, vocabulary is the first thing that is affected which is called lexical attrition.
Language attrition is the process of losing a native or first language. This process is generally caused by both isolation from speakers of the first language ("L1") and the acquisition and use of a second language ("L2"), which interferes with the correct production and comprehension of the first.
The first linguistic system to be affected by first language attrition is the lexicon. The lexical-semantic relationship usually starts to deteriorate first and most quickly, driven by Cross Linguistic Interference (CLI) from the speaker's L2, and it is believed to be exacerbated by continued exposure to, and frequent use of, the L2.
- Language Attrition / Wikipedia