I would guess that the German word that was awkwardly translated as ‘else’ is ‘sonst’: https://en.wiktionary.org/wiki/sonst

That’s just English, right? Except that it isn’t. I can’t use “else” as a conjunction in normal speech, only in computer programs.

There are a few examples of old texts using “else” as “otherwise”. For example from Wycliffe Bible:

Other men see not by any curiosity those things that be in the saintuary, before that those be wrapped; else they shall die.

(Not sure if that can be called “normal speech” though)