I am not known for my exquisite typing.
I like the concept a lot, especially that the words are in Latin which both feels appropriate narratively and challenges the player to pay close attention to spelling.
Highlighting the already typed characters works great, though it was strange when a new enemy's word was already previously typed due to linking to a previous defeat.
The fast moving ones are very rude, even if they have short sequences. And ones which appear from the bottom and right are far easier to deal with than those from the top and left, since you can see the starts of their words to begin with.
With some sound, music and animations this could be quite addictive.