Bach probably never used equal temperament. He did use meantone, which makes E flat higher than D sharp (the spacing is about a third of a tone). Quantz's book on the flute describes flutes of his time as having separate E flat and D sharp keys at the bottom.

One variant of meantone is very close to 19-note-to-the-octave equal temperament. Someone made tenor recorders with extra keys to play in that scale a few years ago. I'd like one if I knew where to get one - the project that created them has been dissolved.

I once met a hammered dulcimer player in Glasgow who uses meantone temperament when playing without a guitarist in the group (guitarists can't do meantone). That was for normal Irish and Scottish folk repertoire. Nyckelharpa players also use temperaments that give pure thirds, it makes a big difference to the resonance of the sympathetic strings.

There is one fiddle tuning in old-time music where this must come up - ADAC#. You'd probably want the C# to be a pure major third above the higher A, i.e quite a bit flat of equally tempered.