There should not be any significant difference between PT+PT and PT+HD when it comes to light passing through the light shader, and in case there is, i would rather use PT+HD, and increase translucency of light shade, than use PT+PT, because PT+HD will give you a lot more reasonable rendertime.
I believe many of the problems in your scene might be caused by improper material setup. Material converter by DeadClown is really great for MR's Arch&Design materials, but is not remotely reliable for Vray materials.
My suggestion would be to:
1: resave scene as a new file
2: delete all materials
3: apply diffuse gray (RGB 160 to 170) material on everything
4: set GI to PT+HD
5: hide glass in windows and do the lighting first (enviro HDRI + interior lamps)
6: unhide glass planes in windows, create glass material for them, and make sure they don't impact performance (twosided glass material)
7: start with materials of objects close to light sources, such as lamp shades, and observe how they affect amount of noise in scene, avoid glossy refraction if possible, and use translucency instead. Avoid using opacity value at all cost if possible.
8: add rest of materials one by one. Make sure you have control over them, so do them manually (no conversion)
9: for optimal performance, try to avoid fakes, especially disabling shadow casting.
It might imply that if you disable shadow casting of a light shade for example, it will make rendering faster, but in Corona, it can actually impact performance in a negative way.