>No one writes animé anymore, why isn't fandom complaining about that?

Because there's no romanisation system that transliterates メ as mé. As such, the spelling 'animé' has always been wrong. I'm not sure why people spelled it this way, but it's probably either to prevent people from pronouncing it all English-like or because they thought it was derived from the French word animé.

>When I see the word "Fuka" in the context of a Japanese comic book, I pronounce it it "foo-kah." Are you saying that's wrong?

Considering the Japanese 'u' isn't pronounced like the English 'oo', I'd say so.
As for the difference between Fuuka and Fuka... 'Fu' takes one mora, 'Fuu' takes two morae. In other words, it takes twice as long to pronounce. Considering that Fuka has two morae and Fuuka three, that makes a lot of difference.