Some terms should be left untranslated only when changing the honorific suffix results in a different tone toward the character, or the term has multiple meanings in different contexts.
For example: onii-chan, onii-san, onii-tan, nii-san, nii-sama
or,
sensei can be used for teachers, mentors, or simply respectful manner toward middle age men (usually someone in politics scenario).
Terms like okyaku-sama or waka/waka-sama however, only has one meaning, or one tone: a polite attitude toward someone of higher status, higher authority.
While okyaku-sama is widely used in various contexts: be it convenience store, restaurant, hotel/inn, private investigation, or even soapland, it has no secondary meaning, nor tone, and can be simply translated as "Dear customer" or "Dear guest".
The same goes for waka/waka-sama: the ones who use that terms are either servants of Makoto, employees of Kuzunoha store, or residents of the demiplane, and they all have the same attitude toward him; the way Tomoe call him is no different, even if she was roleplaying edo period drama. "Young master" was used by both Uxtef & Soseki before, and there was no misunderstanding in those chapters either.
If the way characters address each other should be left untouched, then it should be applied for even Aqua&Eris toward customers, as well as Morris towards the Rembrandt siblings (ojou-sama).