Hum. I have a hard time deciding what i think of this.
For several cards, i think it's fair game to use the male form. Whyever this is the case, the male form in german is still kind of regarded as the word for a profession per se: A female can be a "Bäcker", but a male can't be a "Bäckerin". Writing "Bäcker" there doesn't line up with the picture, but it does a better job at including all bakers than "Bäckerin" does.
Now, the question is whether you want to think of Dominion cards as individual people, or about a name for a set of people. I actually think the original question in the german forum reflects the problem rather accurately: Are we talking about Candice*, the baker from around the corner, or about the set of all people with her profession? I personally think Dominion is not consistent here: You can't have 10 times the same person, but of course Peasant and Page tell stories of individuals. A long time ago people apparently decided to go with the abstract profession thing, and it worked fine for a while, because theonly relevant females were Witches, and well, Witches are kind of their own profession and some of the few examples where the female form is the standard. I assume a Nurse would have been the same (at least with a female depicted). With the increase in women (on cards named after the person shown), this problem surfaced, and well, they apparently decided to go through with it.
I agree it's not necessarily a good choice. Baker is a little weird, but hey, again, it's a profession, see my point above. For Hero, i think it's ridiculous to use the male form, as obviously the cards depict one character's story. Even when going with the male form usually, they should have made an exception here. Also, i honestly doubt a male nurse would be translated as "Krankenschwester", even though that's (or used to be) the standard expression here.
*This is actually the name our group uses to refer to Baker. Don't ask why.