In the dragon ball franchise, why 筋斗雲 is sometimes translated as "golden fighting cloud" instead of "somersault cloud"?

Because using the same word repeatedly gets boring?

It’s a golden cloud from which Son Goku fights. It isn’t inaccurate.

I only hope that the translator did not arbitrarily designed his own name for the object.

Such things happen during translation, due to the differences in culture and idiomatic speech.

Flying Nimbus doesn’t mean “somersault cloud” or “golden fighting cloud”... And that has no bearing on the story at all.

Flying Nimbus is the name spoken of by the dub, but I’m not speaking of the dub, but of the translation of the japanese name.

I’m aware of that.

If you’re trying to learn Japanese by reading manga, you’ll have to come to terms with the fact that translations are often not literal.

In Chinese the tone changes the meaning. The first character has the sound jin which means sinew or tendon but spoken with a different tone means gold. The first two characters together mean somersault.