The verb "to determine" has two (relevant) meanings that are quite different. Because of a quirk of phrasing, it is exactly the words "have sold" versus "sell" that let us know which sense is meant here. So no, you can't swap them without changing the meaning.
Sense 1: "To ascertain definitely"
(Loosely, this sense is about figuring out what happened in the past.)
This is the intended meaning. The US Commerce Department "ascertained definitely" that ZTE sold goods to Iran.
This is basically the same as what you say in your edit, that the US "found out" that it happened. But as commenter @Minty says, there's a difference between "finding out" and "determining". When you find something out, it's new—you've only just discovered (or been given) the evidence. When you determine something, you might have had the evidence for a long time, but you've been taking your time to examine the evidence and are just now making an official statement about what you've found to be true.
Sense 2: "To have a fixed intention of"
(Loosely, this sense is about what someone intends to happen in the future.)
This is not the intended meaning. If understood this way, the sentence would mean that ZTE "had a fixed intention" to sell goods to Iran: they planned to do it, and they were going to stick to those plans even if problems came up (which is the difference between wanting to do something and being determined to do it).
Why does "have sold" versus "sell" matter?
The problem is that Sense 2 is usually used in the passive voice: "I was determined to answer this question", not "I determined to answer this question". This makes it possible to be confused about who the subject is—who is doing the determining? Am I making up my own mind (Sense 2)? Or is someone else making a decision about me (Sense 1)?
Sense 2 should be followed by an infinitive in simple aspect, no matter the conjugation of "to determine":
I am determined to answer this question. (I have strong plans to do it.)
I was determined to answer this question. (I had strong plans to do it.)
ZTE was determined to sell goods to Iran. (They had strong plans to do it.)
On the other hand, Sense 1 will commonly be followed by the perfect aspect. (We typically talk about conclusions that were reached in the past, and so the thing the decision was about is "over and done with", which is what the perfect indicates.)
I was determined to have answered the question. (Someone decided I definitely gave an answer.)
ZTE was determined to have sold goods to Iran. (Someone decided they definitely sold the goods.)