I already have tried another outdated addon though, one from 2014 via twitch app, and another from 2017 via the twitch app, and they both seem to not work. (One of them is actually updated here but not via the curse network.)
For instance, the MiniMap from Fyrakin on twitch/curse isn't updated enough to be working currently, but it's updated here on esoui.
This one just throws a LUI error and doesn't even initialize:
https://www.curseforge.com/teso/teso...charge-counter
So, not all outdated addons will work even with outdated enabled. But, whatever.