You might be able to get some of the functionality there via plugins?
Godot and unity both got some of the level editing stuff via plugins already. Godot has several!
They are open source, so you maybe we can study how they work
So it's just a matter of time someone writes a similar thing for construct in javascipt?
Btw there was a petition to open source that ubisoft engine (ubiart):
Regardless of how many people signt it, that will never happen