Hey, thanks for the feedback!
About WPM, it's very plausible that it's broken. I changed how it's calculated not long before the demo and I may have made a mistake. Thanks for the reporting this issue!
There's already a key to reset the typing buffer: it's delete by default but you can rebind it.
Most if not all keyboards should work for playing the game. The keyboard support is specifically for the virtual keyboard drawn on screen if you want to edit which keys are enabled. I originally wanted to support QWERTZ for that but dropped it due to limited time. I decided to just stick with keyboard patterns used in the countries where the two languages supported by the game are spoken. It also changes the keys used to scroll through the menus if you want to use WASD or the equivalent on other keyboards.