There is no reason to doubt the authenticity of the accents added in the proofreading of FE (→EE) on c in bar 486 and on C in bar 487. In turn, it is not clear what kind of accents Chopin had in mind, since it is difficult to assume that he would have liked to differentiate between them. According to us, it is long accents that are more likely, since a shift of the shorter sign (in bar 486) may indicate that the accent written by Chopin was longer than the one printed in FE. However, it is only a suspicion, hence both the long accents suggested in the main text and the short accents in EE may be considered equal variants.
Compare the passage in the sources »
category imprint: Graphic ambiguousness; Differences between sources
issues: Long accents, EE inaccuracies, Authentic corrections of FE
notation: Articulation, Accents, Hairpins