It seems fairly straightforward but somewhat counterintuitive that in bar 22, the natural for C6 is to make sure we don't continue on with the flat one from the previous measure. But since it's a different measure, it should ideally be in parentheses, as a courtesy accidental. Unless the tie across a measure boundary somehow annuls that convention. Notably, while the link and the .png are from a Soviet edition, I found a (seemingly) French edition which did have the parentheses. (Still, in bar 57 of the Soviet edition, there's an accidental with parens as well so it's not like they had a different convention.)
Similarly, for bar 24, I am wondering about the double flats. B5 which is being double-flattened is already pretty flat given des-dur. My understanding has been that the double-flat-on-B5 is played as A5, not A5 flat -- which also seems counterintuitive since there are 2 accidental flats not after a natural + 1 key flat which should theoretically bring it down to A5 flat. (The aforementioned understanding of mine received some justification from measure 56 of the prelude where tripling the flats made zero sense.)
Regardless, thanks for looking at this! Also, interestingly, double flats in that fugue are swarming whereas double sharps are hardly any -- which makes sense in terms of consistency and is easier to play, but sort of strange to observe.
[...] Hope that helps, and feel free to ask more in depth if you want. I love explaining this sh*t