Don't worry, your details already help a lot! I will look into it later this week.
The published version indeed has one bug regarding inserts referencing a deleted element. Maybe that is (part of) what you saw as well. I've fixed that locally already, but unfortunately only after I've made signifant other changes which are still to be refactored & published ;-). Probably time to just backport the fix and release it.
May I ask which inputs produced invalid results for you and which parts you consider hacky? I'd very much like to improve the implementation, so a reply here or an issue on e.g. GitHub would be highly appreciated. Thanks!