If it is only "kind of strong" shouldn't it be forteta?
It would be, but in this sentence I believe "that kind of..." means "that sort of/that type of..." rather than "that somewhat..." .
Well don't I feel smart now...
You're learning a constructed lingua franca by interacting with a screen. You should feel smart.
What you're thinking of is the adjective phrase "kind-of-strong", which should be hyphenated as so.
This sentence feels rather strange for me.