"Anna is a good artist."
Translation:Анна — хороший художник.
since we are referring to a woman, I would expect only the "female" version of the sentence to be accepted. Duo accepts both versions (male and female), but seems to prefer the male one. is it really common in such sentences to use "male" in the second clause, regardless of the gender in the first one?
Specifically female nouns referring to professions, titles and alike are quite troublesome in Russian. Some are pretty much mandatory and cannot be replaced with their “male” equivalents, like княгиня, принцесса "princess", служанка "servant", певица "singer", актриса "actress". In some cases you can use either: both художник and художница work fine for "artist" and female поэт "poet" can be called поэтесса.
Some occupations are normally masculine, but have colloquial female forms. Examples include библиотекарша "librarian", билетёрша "ticket seller", директриса "director (head of the school)", комендантша "superintendent".
However, certain feminine nouns are disrepectful and even derogatory, like врачиха "doctor" or профессорша "professor".
Sometimes they can also mean the wife of the said person, e.g. бригадирша can describe both a female бригадир and brigadier's wife.
Another problem is that sometimes the possible form already means something else. Индеец is Native American, but its counterpart индейка is a turkey.
Many other similar words don't even have a feminine form: инженер, министр, вождь, борец, лауреат, etc. And then there are female-only professions, like балерина, which has артист балета as its masculine counterpart.
There is no real pattern neither to formation of these nouns nor to whether you should actually use the feminine form. This was written more or less based on this article. I'm afraid I don't have time to translate the whole thing, but I can't find any better explanation.
To add to that great explanation, my Russian teacher told us that in the case of professions where titles have both masculine and feminine forms (like преподаватель/преподавательница, teacher), most Russian women prefer to be referred to by the masculine version, because using the feminine one is akin to considering two "classes" of teachers, "преподаватели" being superior to "преподавательницы", even though they are not outright derogatory like врачиха.
The same happens in Greek as well. The words for female doctor and Member of Parliament come to mind. It's probably because those terms were coined when women in these professions were a novelty or even non-existant, with the sole intention to make fun of them. They sound cutesy and people used to openly laugh at them.
In Spanish, the words for femsle professionals are not offensive at all. Au contraire, a female professional WANTS to have her female word, even when the word itself is grsmmstically incorrect, such as the famous case of the word "presidenta", which breals the rule saying that words ending in -ente can be both female and male adjectives/nouns. (as in " La estudiante" = The female student)