When editing Lexeme entity using wbeditentity API action, API response after successful edit contains (empty) fields with labels, descriptions and aliases.
wbeditentity should be either adjusted so it returns fields relevant to the edited entity (ie. labels, descriptions and aliases when Item is edited, and lemmas, language and lexical category when Lexeme entity is edited), or not return changed entity data at all.
Decision on which way to choose depends on whether data returned in the API response is actually used anywhere, I believe.