Translation:Not even after one hour did he find a toilet.
This is a guess as to why "hasn't found" is not accepted.
The Czech najít is a perfective verb, meaning the action is over. The English "hasn't found" suggests that the action has not yet been completed and is still going on -- he started his search an hour ago and is still trying to find the bathroom (and maybe he's not very happy about that...)
I think it is just missing. U2 song: I still haven't found what I'm looking for. - Stále jsem nenašel/nenalezl, co hledám.
It is perfective, but because the search wasn't succesful, the search might or might not be still going on.
There is a time specified here, but, to my limited knowledge, not in the way that would rule out present simple. I will add it later.
But here we would expect more than just a sentence. The sentence discussions are mainly for questions, not just for repeating a translation that had just been reported.