The error message looks like the mod is for a game using a different version of Ren'Py. Presumably you applied the mod to the wrong version of the game. Current game versions are the final pre-remake versions of Act I and Act II and the current version of the remake of Act I. The all-in-one version of the mod seems to consist of various parts, some of which are for a certain version of Act I (the final one?), and some for a certain version of Act II. Your error message wouldn't surprise me if you had applied an Act I mod to Act II or vice versa.
(Unlike the majority of Ren'Py games with versions that have episodes in their names, where this just indicates where the game currently ends, Ataegina is actually split into two acts which constitute separate standalone games.)