Hi,
> >> xin and I have found some translations or suggestions by new
> >> contributors on Weblate. Like they are new, they made some mistakes.
> >> 
> >> How can we contact this new contributors? In fact, on their profile page
> >> on weblate, we don't have access to they're mail address.
> >> 
> >> Any idea how we can contact them?
just add a comment to the translations, than the author may see that. If you 
found any way to to reach the user, than please tell, as we want to add this 
to the user documentation for using Weblate, as this may be not the only case, 
that we hit this issue.
I checked the documentation: with Weblate 3.6[1] it should be possible to 
mention users directly in comments. At least the documentation for 3.10.1 have 
added it to the documentation:
https://docs.weblate.org/en/weblate-3.10.1/user/translating.html#comments
If you don't find any way to reach this user at the moment the admins can see 
their email address and could sent an email to that user. But I really would 
avoid this step as this would mean manual work.
I hope, that zen and I will find time the next weeks to update Weblate.
hefee
[1] 
https://docs.weblate.org/en/weblate-3.10.1/changes.html#weblate-3-6