But the football club is named after the city, no ?
It is, but it's a separate entity. Genova is the Italian name for the city, but the club uses the English name Genoa, so you don't change it back.
In that one case yes but the others aren't are they ?
I'm lost with what you're talking about here. Cities have different names, depending on language, because they are centuries old and fluid. Football club's are limited companies, who have an official name that is fixed.