"Éva is painting men and women."
Translation:Éva férfiakat és nőket fest.
It sounds a bit like the relation between the objects and the verb is different. Probably because "Éva fest" is a complete sentence on its own, which renders the rest quite negligible. Even though it's not wrong, I can't hear it without thinking of how much we know pretty much nothing about what Éva is painting. :D
I think it should be accepted, too. The meaning of your sentence is different, than the original.
"Férfiakat és nőket Éva fest" = ÉVA is painting men and women, not someone else.
"Éva férfiakat és nőket fest" = "Férfiakat és nőket fest Éva" = These sentences emphasize what Éva is painting: men and women.
You are right, it's not invalid but still, odd enough to note. Setting the topic as "men and women" and telling that it's Éva who paints these.
"Syntax" happens to be quite complex which resulted into the following status quo... everyone tries to explain word order everywhere. It's far from optimal but I think one can learn quite a lot by sticking around and reading comments.
When is it not OK to topicalize an object? As noted in a comment below, Férfiakat és nőket Éva fest seems fine, but is this not good because it is emphasizing the object? And why does the correct translation place the verb at the very end of the sentence? Should we default to an Subject-Object-Verb structure when we don't know which word order to use?