After long trying I have been able to create a texture set that at least for me is s in some way acceptable. Do not know if VRC uses some special settings of the shaders or someting, but the result is more see through but also in some way produces shiny or bright glass....you may try and see if it is useful for you.
Here they are:
https://1drv.ms/u/s!AhmLWyeq-a6oi5NPtks ... A?e=iekOc5Updated link January, 26th 2020, with a documentation for modifying the Geo files of the model - please do this only if you have some experience with RWTools. Sidewindows still darker than front and rear windows - hoping to ge this fixed also .
I assume you make a backup of the files before, anyhow a safe approach is to have the addon uninstalled and install it again by using the STEAM client if you missed a backup and o no like the replacement textures.
Installation:
Open the archive and put the two files in the following path in your TS2020 installation:
Assets\VRC\Dash8_00\RailVehicles\Diesel\C398\NS01\Engine1\Textures
Assets\VRC\Dash8_00\RailVehicles\Diesel\C398\NS01\Engine2\Textures
Assets\VRC\Dash8_00\RailVehicles\Diesel\C398\CR01\Engine1\Textures
Confirm overwrite and try out the new view.