Loading Screen System (Level Transitions w/ Progress)

The system is not set up to hook into streaming activity performed by external means / other modules - it does not check what levels World Comp is trying to load.
Right now, you would have to provide the LSS with a list of particular levels - this would work even if World Composition initiated the loading (as LSS would still check progress of all selected levels). But, as you pointed out, that isn’t exactly practical with a WC setup, as you don’t know which levels are relevant.

I have an idea for such functionality, that would allow the LSS to monitor any and all streaming levels for loading activity and provide a loading screen accordingly. For World Composition, this, of course, would only make sense for the start of the level (or after teleportation, e.g. fast travel), but not for any seamless loading that would occur based on distance while the character is moving around the world.

I’ll figure something out after I’m finished with the current update (Replication) and, if feasible, will add it as a next update.