Is this normal? Does this happen to everyone?
Yes, due to the way input in handled, one key at a time, which means that it detects when you press the “next letter needs an accent mark” key (i.e., the so-called “dead keys”), and it shows its name without waiting for the next letter.
If you want, you can filter out these keys in line 275 of IFEngine/js/CRT.js, however the game’s license forbids modifications to its code, therefore i would avoid it.