Yep, consider the app abandoned. I've made an edit. I've dug around for weeks, and, unfortunately, been unable to come up with a method to make this work on custom UIs or even slightly modified ROMs.
The app works reasonably fine on standard AOSP; perhaps there's a more unified, unmodified codebase in Lollipop, which I will dig into when and if Xposed is ported.
That said, the app is open source - feel free to dig around and see if you can spot anything. I'm certainly no genius, and I'm sure there's someone more experienced than me who may want to contribute a patch for their ROM.
Cheers, thank you for your time, and sorry for the uncertainty about the whole thing.