The entry in FEH may define the authentic variant of the beginning or perhaps also of the ending of the trill (in order to implement the latter, one can use the version of GE3 in the note applying to the 1st of the small notes ending the trill). However, one cannot exclude that the added diagonal sharp may be simply Chopin's characteristic teaching mark and not a 
raising f
1 to f
1. Anyhow, in order to denote elements of a diminished seventh chord, Chopin would use notes separated both by a semitone and a whole tone, cf. e.g. the ending of the trill in bar 614 (whole tone) or a written-out turn in the 2nd mov. of the Concerto, bar 68 (semitone). Interesting variants in a similar context, yet probably resulting from mistakes of the first edition, are to be found in the Etude in C minor, op. 10 no. 4, bars 15 and 19.
Compare the passage in the sources »
category imprint: Graphic ambiguousness; Differences between sources; Corrections & alterations
issues: Annotations in teaching copies, Authentic post-publication changes and variants, Annotations in FEH
notation: Pitch