This translation sounds much more natural: "Your aunt talked about someone named Frantisek." It should be accepted as correct.
The English translation is very strange and unclear in meaning.
I think it actually translates to 'Your aunt was talking about some [person called] František'. The speaker here isn't sure who František is.
Proč Your aunt told about some František nepřijímá?
tell is used with an object (sort of like in dative) "tell someone something"
Talked can be used here.
However, these are the simple rules taught to us ESL speakers. In practice it could be a bit looser and allowable in some situations...
we would usually say 'someone called Frantisek' but I suppose in very colloquial english it might be said
Why can I use "Your aunt told about some František." Thank you very much In advance.
See the answer to NinaOBel. We would need some addressee of the talk (told me, told us, told him...).
Sorry it is my mistake. Thanks again.