That was my reaction too. 350ms latency was no problem in that demo, after the low-baud-rate high-latency terminal mode connections I’ve used earlier in life.
I not only type easily completely free of feedback, I can recognize I’ve made a typo, back up and correct it, and continue before anything displays. If I’m not sure what I mistyped, then I just pause and wait for the whole line to display before correcting it.
It’s just a different typing mode to get into.
Ironically, due to some glitch in Discourse/Firefox/Noscript, I can’t see the cursor or highlighted text when typing here, so it’s a closely related experience when it comes to editing this reply.