The incomplete and different slurring in EE results most probably from inaccuracy and mistakes by the engraver. The two-bar slur in bars 54-55 (and a similar one in bar 56-57) is placed over a figurate passage that resembles a uniform, ascending-descending arpeggio, and encompasses a half of line. It has not much in common either with the slurs in A, or with the real phrasing.
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, Errors in EE
notation: Slurs