Crystallizing mixed language in poetry?

Says Sarah Grey Thomson on p. 215 of Language Contact (2001):

"Some groups of Dutch teenagers – all of whom know at least some English – lard their Dutch sentences with English words, to such an extent that many sentences will have more English words than Dutch words. This is not a mixed language, or any language; it almost surely is not crystallized into a speech form with set rules of combination that must be learned, but is rather produced in an ad-hoc way, sentence by sentence and speaker by speaker, without any consistency in the choice of particular English inserts. ... The fact that the teenagers can do this deliberately, for reasons of fashion, provides further evidence that speakers can combine the lexicon of one language with the grammar of another whenever they wish to. All they need is a motive; and all that’s needed to produce a fully crystallized bilingual mixed language by this means is a strong motive that is shared by a group of people. "

Two thoughts arise related to poetry: first, since poetry is an artificial language in the sense that it does not naturally spring from normal conversations, perhaps we can formulate a set of rules that will govern or explain the use of words in another language in a poem; second, since there is a group of people that read and write poetry (the poetry community or the poetry-competent community), perhaps we can produce the fully crystallized "language" of poetry.