Hi Aleksander, and thanks for your post.
Sorry for the late answer, I'll only be able to look at it tomorrow, and then I'll answer you here.
For the moment, I can only tell you the Keyboard lib is different depending on your Arduino version.
We didn't really forget to include Keyboard.h, it's just that with my version, I don't need it!
But you're right, I'll add it to be compatible with most versions, thanks for the idea
The result may be different with the OS too, the \t, \n, etc. always produce differents results.
Anyway, I'll look at it and keep you posted.