So, do you expect to do a scenery upgrade to solve all of the above?
Since the problem appears only after adding the Aerosoft scenery, I don't see why it's expected we should release a fix, considering FSDT KLAS was released way BEFORE US Cities X so, it's usually the one that releases last that provides patches if they have compatibility issues with products already on the market.
At least, this is what users usually expects from us when we release something that might affect something else released earlier. Case in point, we include some fixes for Megascenery Hawaii in the PHNL installer, because Megascenery was already on the market when PHNL was released.
or is it too complex to do and we have to use one scene or the other (in this case, aerosoft scenery seems better as it covers a larger area.
I don't think that, after removing the mesh_terrain.bgl file, the area is unusable.
And of course, such choice or saying the Aerosoft "seems better" doesn't make any sense, since it covers just the city, if you go remove FSDT KLAS you'll revert to the default airport. Considering that default scenery for KLAS already comes with a decent and detailed city representation, one would think you'd prefer using the more detailed airport instead, if forced to choose. But again, I don't think the current situation would make the combination not usable.