by Chacal » Sat Dec 29, 2012 4:00 pm
No.
It verifies files that were downloaded from Steam only.
More precisely, it has a list of default files and their checksums and goes down the list.
If any of these files is missing or has changed, then it will download it again from Steam.
3rd-party content such as routes and scenarios is invisible to this process because those files are not on the list.
The only things that you could lose are modifications that you made to default files.
For example, if you applied simer4's sound pack for the default SD40-2, a verify cache will reverse the change and you will have to reapply the pack.
Over the hill and gathering speed