I imagine there's a more efficient way to handle typing for these low bandwidth cases. Maybe chording of common syllables. The layout in the article looks inefficient. You can probably lose accuracy in text to have easier 'speaking.' If you wanted to say 'father' you'd have to hunt and peck six letters. With chording you could click on 'fa' and 'der' and it should be understandable via context. Toss in some predictive logic and you can chord words at once or even entire sentences. Probably easier said than done, of course.
It's a miracle every time someone manages to put the signals together to get something meaningful done.
An important concept here is the 100-steps-rule (https://www.teco.edu/~albrecht/neuro/html/node7.html) - neurons are SLOW! You can out-jog most non-myelinated neural signals, and the vast majority of sensory and motor computations finish in the order of 100 "clock cycles".
Write me a computer vision algorithm that has enough parallelism to complete in 100 cycles, and we can talk about understanding the biological brain compute structure and true brain-computer interfaces.
https://en.wikipedia.org/wiki/Language_of_thought_hypothesis