Lol, I am not American

Then you're fine. If you were in the USA, getting sued was a legit possibility.

Also rabies is not exactly a misplaced worry. Even in house cats. If your cat spends any time outside near trees, interaction with squirrels is possible. Squirrels carry rabies. So your cat getting infected is a realistic concern if the cat has not been vaccinated for rabies.

But again, if you're not in the US, you are mostly covered legally. If your cat is not inoculated for rabies, the kid getting rabies shots as precaution is not a bad idea.

Also, cat scratch fever is possible other than rabies. If the events happened as described, the mother is the real idiot and asshole here, assuming animals behave the same at all times. Kids are stupid because they're kids. You did what was required in terms of warning the mother.