maflcko pointed out in #30267#pullrequestreview-2155603386 that some error strings were being translated unneccessarily and incorrectly in #30267.
Switch them to untranslated for now. In the future if we add a GUI feature for loading snapshots, and it seems like it could be possible to trigger some of the errors, they could be translated at that point.
Also remove a newline in a thrown RPC exception.