You can report that as an alternate translation. Can you access the Tips and Notes here if you scroll down at this page on your browser? https://www.duolingo.com/skill/cy/Work That red banner is standard to all the comment pages just to remind people to stick to discussing the sentence as we do have children on this site. Many comments will soon appear. Here is a useful grammar page: https://en.wikipedia.org/wiki/Welsh_syntax
athro and athrawes are generally interchangeable unless there is some to indicate that only one or the other can be used.
If you raise your query from the sentence where you found the problem, we can either fix it very quickly or explain why it should not be changed in that particular case.
I've edited the pictures, well Duolingo has now given us a better group of pictures to use with the word teacher.
Although only one of them is a female teacher, but at least they are teachers. Hopefully this will help.
There's probably no discuss option because this is a picture question and Duolingo doesn't consider the words taught in its usual way.
Either 'athro' or 'athrawes' should work for any translation from 'teacher'.
If it doesn't it could either be an incorrect deleted sentence floating around in the database or something we've missed. If you either list it here or report it we'll fix it if we can.
Thanks for the comment.
The word for a male teacher is 'athro'.
Athrawes is probably analogous to 'schoolmistress' in English while 'athro' would be the equivalent of 'schoolmaster'; although athro can also be used for 'professor'.
While many gendered nouns are disappearing in Welsh, as in English, both 'athro' and 'athrawes' are still commonly used.