Normally words don't change gender. They may loose their gender, OK, so it should be "Das Weltenbund". And maybe that apocryphic way of connecting words that German uses gets lost, so "Das Weltbund" sounds reasonable. But Anglic is close to English (except for humaniti and such words, I guess), so why should German change that much?
On the other hand I do remember someone called Force-Ka-man or some such. That would be horrific English for Force Commander...