As referenced in the thread pertaining to loading issues in 0.18 ("Won't load 0.18.1"), I get an error on startup reading Failed to load mods: File not found: GirlCharacter/images/level2addon_dead_mask.png when I load the mod with normal quality graphics in 0.17. On High quality graphics, I get no such error, and have switched between both to verify that the error persists on normal quality.

Are you on version 1.0.0? Version 1.0.1 doesn't work with 0.17 just in case. But yeah, I guess the bug is there if you're on normal quality sprites, but it shouldn't happen if you use high quality sprites