The graphical and database interfaces for FreePBX11 and above changed dramatically and radically from 10 (which is what I wrote the original program for). As odd as it sounds, there just isn't a lot of demand for a graphical interface for managing these phones. You're probably the fourth person to ask since FreePBX 11 was released.
I've been busy with lots of other stuff, including working at my day job (look for "Cynjut" on the Internet - that's almost always me) and the "orange one" is keeping us pretty busy lately.
If you follow the advice I provided in the "Chan-SCCP-B for FreePBX Wiki article (splitting the file into line and device components), the system really is pretty simple to maintain even without a GUI.
I'd love to get back to it, but my phone customers never change their configs, my day job isn't interested in it, and I have more work than I can get done with other stuff. Sorry.
The code is out there on GitHub and SourceForge. One other guy said he was going to make it work with the new database and graphical stuff from FreePBX 11, but I never heard back from him. Since the only thing he needed to do was the graphics code, I have to assume it's more daunting than he assumed.