Interestingly, when I searched "hister" on English Wikipedia, I was sent to https://en.wikipedia.org/wiki/Danube#Names_and_etymology

Where it says that “Hister” is a variant of its Latin name.

I think the name is lovely with no reason to change. Surely there are few people who would connect this with silly medieval superstition. Perhaps you can take part in wiping out that association.