[unfamiliar]

To be fair, most humans would probably have difficulty interpreting that. The problem with a lot of these tools is that they have no idea of context. A human reading your matrix will know why you are writing it out, and probably how it is expected to fit into the larger text, and therefore has a lot of contextual information prompting them towards interpreting your chicken scratch as a matrix, not a vector.

I tried to write the equivalent of \widetilde{u} which it interpreted as u^n. On reflection, what I wrote did look like an n above the u. But if you work in the same field as me, you would immediately assume it was a widetilde.