We try to program many of our addon projects on ULib and standard Lua (not Glua).
As you might expect, sometimes we can't avoid using Glua due to game functionality (prop watching, etc)
At this moment, to my knowledge, there are no individual plans to convert any single side project other than ULib and ULX.
It's quite possible as we convert ULib, some of our addons may just start working in the new code.
Once we've released a stable release of ULib and ULX AFTER the official release of the new Gmod, try this again.
If it doesn't work, and you've tried removing all other addons, and are operating in sandbox mode (because we start with only sandbox), then make a report with as much information as you can provide, not just "it doesn't work in GM13".