First of all, I’m not an employee of Athom. Like you, I’m just a user who does the job as a moderator on a voluntary basis in my free time.
Unfortunately, there is no protection if an app developer stops developing their app, for whatever reason.
Apart from here in the forum, you can try to contact the app developer personally via PM. You can also report the problem on GitHub (link). And when I look at the last entry on GitHub (link), it doesn’t actually look like the app developer had any intention of stopping.
This can of course motivate a developer.
If one of you can program, it would also be possible to fix the bug in the app and make a “pull request” on GitHub, so that the app developer only has to review and release the code.
However, both only make sense if the app developer responds to it.
A community app can of course also be taken over by another developer. But for this you have to contact the current app developer and he has to be willing to hand over the app.
Another possibility would be for another app developer to re-program this app from scratch.
You can also use this link to request an app which then might be developed by Green itself. But, since this community app apparently supports other manufacturers besides just Green, I don’t know if the Green would implement also the other manufactures.
I’m sorry I can’t do more for you.