I have the Curse Client set to not install libraries separately, but installing or updating Bagnon through the Curse Client causes a standalone copy of Ace3 to also be installed. It looks like this is happening because Ace3 is set as a required dependency on the CurseForge project page, rather than an optional one.

i've switched it to be marked as an embedded library instead. does that fix it?

Probably, but it doesn’t seem to have updated on the project page yet. I think it won’t take effect until you post a new version. I’ll let you know if there’s still an issue next time there’s an update.

Did the curse client thing happen? :)

Yep, seems to be fixed! Thanks! :)