I certainly wasn't aware Barakta had any language impairment other than, obviously, deafness.
Yeah, it's a deafness thing. Combination of failure to acquire language fully by osmosis, and poor working memory.
Most noticeable is the way she's only got a one-word noun register
[1], so will sometimes contradict herself by repeating the same one in the second half of the sentence. "Windows has horrible fonts so I prefer to use Windows" sort of thing. Similarly, failure to correctly apply negation, so she'll say the exact opposite of what she means. In both cases, she won't 'hear' that she's done it and correct herself as you or I might. Happens more frequently in speech, but sometimes creeps into her writing when tired.
She's had to work on various quirks in her formal writing over the years. She really should have had teacher-of-the-deaf support in later years of education (she got some as a postgraduate student), but if a deaf person is likely to get a couple of GCSEs they're Not A Priority.
Obviously the problem comes when I - a product of an 80s/90s grammar-free education - have to proof-read her work. Factual errors and typos and such are fine, but the problem comes when something feels wrong, but I struggle to tell whether it's violating an intangible grammar rule, or just not my preferred style.
[1] I'm making her sound like the Apollo guidance and navigation computer.