Ok I took the time to re-try using that addon in my prototype, I reverted my changes and that time put the content of the zip in the root directory of the project (which is what that addon expects, with hard-coded paths…) Once I removed my scene’s environment (that was from “Instant Realistic Light” and just added the GodotSky node, I am now able to see the sky properly, with decent lighting. I with there was an easy way to mix both though, but I can do an approximation manually.
Anyway, it works (ignoring the hardcoded paths issue). (again using v4.2.2)