[astrange]

> Funny enough on Shakugan no Shana, there is a character that says -desu a lot and that not being translated and also explained to me when it first appeared, provided the ground to figure out a bit of the background.

That's a joke. You shouldn't literally translate jokes because they won't funny; explaining jokes ruins them. The purpose of watching a TV show is to be entertained, not for you to learn grammar quirks only used by anime girls, so they should put new jokes there. You have not learned any useful information about Japan or their language by observing someone says desu a lot.

An amusing case when translating for people like this is you often have to translate honorifics into other honorifics, because they don't actually know all of them but just get upset when they don't see the few they do know. So -dono -me might get left out or shinobi/bushi changed to ninja/samurai.

[Fire-Dragon-DoL]

No, -desu was explained at the beginning of the episode, you have a whole 20 minutes (or more than 1 episode, I can't remember) to get to that point, so the joke worked perfectly fine as it was originally