I don't know to what extent we can tell someone's education from the way they speak. It might just be the grammar she was raised with, it's pretty standard AAVE in some areas to speak that way and it doesn't denote a lack of education (but it's true that a lot of people raised speaking that way, who do get an upper education, will train themselves out of speaking in their normal way so they aren't judged).
Thank you for this teaching moment
I live in Europe, which this way of speaking
does immediately ring a bell.
As a polyglot, I can assure you how much you learn about a person only from her linguistincs!
I know that most people mostly rely on non-verbal cues, thus paying much less attention to the linguistics itself.
But in my personal experience, detecting lying is better done through the speech and content analysis than non-verbal cues. Thus, an anxious person who fidgets, and so on, you can better analyse the cause of her anxiety through a throughout speech analysis than from non-verbal cues.
Her speech, to a certain extent, speaks about her education level, her intellectual abilities, her abilities to process emotions...
Though it can be limited by cultural aspects.
Also, you can picck important cultural clues by solely analysing speech.
Two examples in English:
1) If the person says, EX: "flavour" instead of "flavor", you can be certain that she is
not of Northern American education.
A Northern American speaker would say "flavor". An UK, SA, NZ, AUS, African, maybe Jamaican would say "flavour".
2) Another example giving clues to someone's past is hearing expressions you've never heard before, and you wonder what do they mean. EX: "Does she really choose to live in the Gramadoelas?" is not easily understable for a US native
unless he has family or friends in South Africa. In SA, "living in the Gramadoelas" means living in the middle of nowhere.
In Australia, NZ, you would had said "living in the outback" instead of "living in the Gramadoelas"
Source:
Oxford English Dictionary adds new entries: chuddies, jibbons and fantoosh | Reference and languages books | The Guardian
If the person hasn't lived in SA, you can be sure that she has been in close contacts with SA natives at some point in her life.
I have examples in French, my mother tongue and in Spanish, but I'm not sure they'd convey my point as well as my two examples above.
An example in writing where you can be sure that the person is not a native English speaker in her writing, and is highly relevant in the cyber space. In French, if you see [Question ? Text follows ], [Exclamation ! Text follows], [semicolon ; Text follows] and such, you can be certain that she is a French speaking native.
In French, the cardinal rule is that after a question mark, an exclamation mark, a semicolon... you have to leave a space
before the punctuation sign
and after your punctuation.
They are very subtle clues, but they give you vital clues for finding someone's past identity.
About speech, choosing "China Black" as an alias can point to clues about her past. She can be of Cuban, or at least Carribean descent.
You have a lot of African and Asian descents at Cuba, so "China Black" can point out to her origins.
My clear issue here is that if we start with the names she has given, it is a needle in the haystack because they are so common you spend an inordinate amount on it!
If you pick specific clues from her speech, you can narrow down your searching pool even with limited MP reported info.
Of course, her speech can be affected by being medicated or not, her state of mind on the specific day...
For an European ear, "you is" is such a glaringly unusual way to speak that it does immediately ring a bell.
I conceive that for a native US speaker, it doesn't necessarily raise any question.
But in UK, only people with very severe cognitive impairments can speak in such way.
At least in Europe, "you is" strucks as so unusual you immediately think that something is going on.
Teaching me about AAVE grammar does enhance my sleuthing skills because I can avoid making glaring mistakes.
So, if next time, it helps me see a blatant rule-out, as we say in France, I'll go to bed less stupid! (We even have a site collecting unusual knowledge called after this expression, but the authors took the expression in its litteral sense).
Would you mind telling me in what regions AAVE is widespread?
States or parts of them can be helpful at pointing clues from her past.
I wish I had a complete transcription and a full videotaped interview with China Black for more linguistic clues, cues of a specific neuropsych illness!
I have brain injury from birth, ADHD is one of its sequelaes with a collection of others.
It explains why I want so badly to help finding her identity!
With my very limited means and my disability, maybe we can do it!
Neurosciences are still in its infancy, there is still so much to learn.
But nothing can substitute picking up subtle linguistic clues for directions leading to her identity!
Though I think we can say, statistically, considering her homeless situation and her mental health, it's likely that you're right that she doesn't have any upper education.
Thank you for guiding me for better sleuthing

I wish I could send virtual flowers here but alas! We can't send virtual smells yet!
Edit for spelling, grammar and such. Gee, I should not post after severe sleep deprivation! (went to bed at 3:00am & woken up by a parcel delivery at 8:30am. If it's not being sleep deprived, idk what it is!)