... is there a way to be sure the wallet files have not been corrupted?
If the wallet is MultiBit? No, the last time i checked the wallet is deprecated and people are advised not to use it cause it developer no longer work on it or provide support which is the reason why people complain about it.
... is there the possibility that hascat (or other recovery scripts) is not able to open the wallet even if they find the correct password?
Thank you!
Hascat does not illustrate how wallet cause it own function is to help you recover your lost or forgotten password.