We don't have synonyms for emendation yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are emanation, mentation and exundation.
(n) :
the act of altering for the better, or correcting what is erroneous or faulty; correction; improvement; alteration by editorial criticism, as of a text so as to give a better reading; removal of errors or corruptions from a document; as, the book might be improved by judicious emendations
(n) :
the act of altering for the better, or correcting what is erroneous or faulty; correction; improvement; alteration by editorial criticism, as of a text so as to give a better reading; removal of errors or corruptions from a document; as, the book might be improved by judicious emendations