About the magic institute.

This texture is also used in the selection window – I don't know why. Maybe it's so that mages can approach the guild on tiled/marble flooring and not get their feet dirty. In theory, you can extract the files (using a special archiver) from some file in the Data folder, process them, and put them back in and save them. But there are many files, and it would take a long time to find the exact ones you need, as they have non-standard extensions and you can't view them directly. So, if you're not familiar with this, it will be quite a hassle, and it's probably not worth trying, as the game isn't worth the effort.