The people telling you that Bach is specific about his key are talking about his work on temperament...none of which applies to the cello suites or sonatas and

The people telling you that Bach is specific about his key are talking about his work on temperament...none of which applies to the cello suites or sonatas and partitas for solo violin. The violin family isn't tempered, and wasn't played tempered unless it was playing with a keyboard. On the violin family his choice of keys was driven by the technical requirements of the instrument, what open strings were available, what chords were natural. Transpose them a fifth down and play them with no worries. I certainly transpose the cello suites up an octave and a fifth and play them on violin with no qualms.