The translations of super hero names always confuses me. Some are translated, other are not, some doesn't make any sense,

Most comics are read by kids or teens, and back in the day in LatAm there were laws promoting local language (Spanish and Portuguese) over anglophilic words. Which is why we got stuff like Bruce Wayne = Bruno Diaz, and Speedy = Ricardito. In the 1990s I believe Panini (the italian company) bought the publishing rights to the DC and Marvel and changed a lot of names back to the Original ones.

why the fuck Magnum?

Wonderman would probably be confusing due to the sound W make in portuguese, besides translating to Homem-Maravilha would make people think it was a knockoff of Wonder Woman. Magnum is just a random cool name they though of it back in the day, also it could be a reference to Magnum P.I. idk lol.

cause she has a magnum dong