The real question here is why Viktor constantly needs to portray himself as some omnipotent "we" who decides "what to do about" different words. This seems an unusual fantasy, and an even stranger delusion.
Regarding the words in question, the general answer is that as words become more widely accepted in standard English, they become recognised by dictionaries.
The specific answer, however, is that many words and phrases - perhaps all - are to some extent slurred or abbreviated in informal, uncautious spoken language. These do not need to be registered in dictionaries, not only because they are absent in standard English but also because they are not words and dictionaries are lists of words. Not words, just generalisations about phonetic realisations in rapid speech - rules that operate at a general level, not at the level of individual words. These processes may be described in full grammars, but aren't the purview of dictionaries.
Words like "can't" and "won't" are different, because their origin as contractions is only etymological. Knowing that thoroughly unstressed vowels tend to become schwa, or that the final /v/ of 'of' and 'have' is often dropped before a consonant when the word is highly destressed, or indeed that the final stop of "and" is often likewise dropped (if you're going to put "wanna" in the dictionary, shouldn't you put "fish'n'chips" in too, and every other pair of words with 'and' in the middle?), these are phonological rules that let you work out the surface realisation from the words concerned. But you can't work out the pronounciation of "won't" from "will" and "not" and a phonological rule. "Won't" is an independent word that has to be learnt as a word in its own right.
Perhaps the most borderline case in your examples is "gonna", where the contraction does have a notable vowel change in some dialects (though for be it's mostly /goUnt@/, with the /t/ sometimes elided in rapid speech, and /goUNt@/ and /goUINt@/ both still found in non-marked, non-emphatic circumstances). But I think it's fair to say that's mostly "going" + "to" for most speakers still, in a way that isn't true of "will + not = won't".
[FWIW, all three 'words' sound very American to me, unless in extremely lax, rapid speech where they are clearly just reduced by circumstances. I do hear 'gonna' (i.e. with /V/) sometimes, I think due to filmic influence. 'Wanna' is confined to emulating the speech of babies and Americans. I don't think I've heard 'gotta', except from a child I know who watches too much American TV.)
But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!