Chording keyboards are never likely to become mainstream because they have a steep learning curve. That doesn’t mean they aren’t a great idea or that they don’t work quite well. This looks like an unusually clever implementation of the concept.
The particular application makes a lot of sense. The combination of a wearable keyboard with extremely fast typing and text-to-speech would solve a real problem for people who can’t talk.
Personally, I’ve played around with chording, but came to the conclusion that I actually don’t need that much typing speed. Most of my typing is either coding or writing emails. In either case, I stop to think about what I want to write often enough to keep my maximum word rate quite low. I can type around 90 wpm on a regular keyboard, which is still faster than I can compose.
I suggest that you spend the up-front money to consult with a lawyer. A lot of them will do an initial meeting for relatively little. They will be able to give you some idea of what risk, if any is involved in this. Then you can make a better informed decision about whether to ignore this, fight, or conceded and change the name.
I find out a few years ago that there are whole law firms out there who basically just send threatening letters for low fixed fees. They don’t litigate or even provide real legal advice. It’s one step above selling pages of their letterhead.
You won’t know how serious these people are, or how serious their complaint is, without consulting a lawyer.
Best of luck!