If you are using Adonis’ loadstring you are probably using the Rerubi interpreter I made, in which case you shouldn’t need to use setfenv to begin with, and I wouldn’t expect the fake function it returns to be setfenv-compatible.
You can try using the unaltered version from github and passing the env table as an argument to the wrapper function instead, since I believe the Adonis version is altered and/or out of date.