S. I. Hayakawa, Modern Guide to Synonyms and Related Words (1968) has this interesting discussion of the adjective forms counterfeit and forged as part of a broader discussion of spurious, apocryphal, counterfeit, forged, and shoddy:
spurious, apocryphal, counterfeit, forged, shoddy These words refer to something that is false or worthless, particularly when it is passed off as being genuine or valuable. ...
Counterfeit and forged are exclusively focused on deliberate attempts to deceive or defraud. Most typically, counterfeit pertains to false money, forged to false signatures, as on a check: counterfeit ten-dollar bills; a forged endorsement on the traveler's check. Both words can also apply to anything that is made to pass for something authentic or of value: a counterfeit painting; forged papal decretals. Usually, forged retains some implication of a false signature that seems to make good a product or document, but counterfeit applies more widely to anything insincere: an attempt to deceive the public with their counterfeit optimism over the results of the government action; the counterfeit concern she lavished on her husband in public.
My impression is that in the real world, use of forgery in situations unrelated or minimally related to signatures is quite common. An Ngram chart of instances of the phrase "painting is a forgery" in published works over the period 1800–2015 shows measurable levels of usage of the phrase from as early as the late 1910s and substantial growth in frequency since the 1950s:
Google Books finds an instance of the phrase "painting is a forgery" (as part of a longer phrase "All modern Gothic in painting is a forgery") from 1847, indicating that people were not unanimous in insisting on a signature connection even then. From "Fashion in Art," in The Fine Arts Journal (May 22, 1847):
What has Gothic architecture to do with Gothic painting? Gothic architecture was, in its best period, the perfection of its style; but Gothic painting is, on the contrary, the infancy of arts; its character of style being the manner arising from timidity, and all that quaintness to which the beauty of texture is sacrificed, is but the adoption of something that is only tolerable as being an authentic specimen of the state of progress of the period at which it was executed. All modern Gothic in painting is a forgery; an endeavour to impose the thoughts of one age for those of another. It is a representation of ignorance that is untrue.
Still, the distinction that Hayakawa proposes seems rooted in a real preference in English for "forged signature" over "counterfeit signature" and for "counterfeit money" over "forged money". In the text that the poster asks about, it may well be that the references to forgery and counterfeit in the phrase "which are physically protected against forgery, counterfeit and alteration by security features (3.26)" maintain a distinction between forgery as a fake signature and counterfeit as a fake document.
Henry Black, Black's Law Dictionary, revised fourth edition (1968) suggests that Anglo-American law retains some sense of this distinction as well:
COUNTERFEIT. In criminal law. To forge; to copy or imitate, without authority or right, and with a view to deceive or defraud, by passing the copy or thing forged for that which is original or genuine. Most commonly applied to the fraudulent and criminal imitation of money. [Citations omitted.]
FORGERY. Criminal Law The false making or material altering, with intent to defraud, of any writing which, if genuine, might apparently be of legal efficacy or the foundation of a legal liability. [Citations omitted.] A fraudulent making and alteration of writing to prejudice of another man's right, or a false making, a making malo animo of any instrument, for the purpose of fraud or deceit. [Citations omitted.]
The thing itself, so falsely made, imitated or forged; especially a forged writing. A forged signature is frequently said to be "a forgery."