Hawthorn does not currently grow. Looking at the code, it looks like it is supposed to grow like cactus, but you forgot a call to this.setTickRandomly(true); so it never receives block updates.

Using Stygian End 1.0.4 for Minecraft 1.12.2

should be fixed in my fork (indev) : https://github.com/quentin452/enderoni-continuation/

I doubt this mod will ever be active. Unless you're willing to continue this mod, then its dead.