Japanese to English Art/Literary Cinema, Film, TV, Drama

Dear ProZ members,

I'm translating a monologue explaining the evolution from pidgins to creole languages. The speaker says that when slavery was legal people from various African places had to work together without understanding what the others were saying. Then they started acquiring a broken version of the language spoken by their masters. And then this sentence arrives:

文法的にはめちゃめちゃだし文学的技巧など持ちようもなかった
(Grammatically they were a mess, and they could have no literary technique.)

I was wondering: is the subject of this sentence the broken version of the language or the slaves themselves?
I'd say the slaves, given that a "literary technique" is something possessed by an individual, not a language. And yet めちゃめちゃ sounds more natural to me if referred to a thing, and not to people.

Any hints?

Thank you very much!