Key signature and accidentals – Music Theory Forum

In functional tonal music or modal music with a tonal center, spellings are about meaning, there is nothing higher level. Even in dodecaphonic serialism, music from 12 tone rows one’s spelling may have individual semantic sense. Syntax has semantical sense, or it is error. Or, in the case where it doesn’t matter to the person with the idea (EG., 12-tone practice), there’s nothing to talk about.

So, again, using E in the key of Cb Major or Ab minor is a misspelling unless_there_is_a_good_reason. A leading tone to its #4 F natural for instance.
The only meaning inhering in your question is musical meaning. You aren’t interested, oh well.