As fidvo said, it is potentially risky but not guaranteed to cause danger.
The most likely source of problems is having a folder or file renamed on Windows, which is case-insensitive (but case-preserving)... and then the database believes the file is named one thing when it is really something else.
Windows doesn't care, but linux will be unable to find the file.
...
I have never had problems reading a Linux-created library on a Windows computer, but I have gotten Check Library ==>Missing/Extra formats when going the other way.
It is easy to fix if it happens, just do a Restore Database.
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No idea what happened to your current library though, sorry.
If your backup includes the folder structure used by calibre, you can use Restore Database to rebuild the library based on the
contents of the backup files.
Alternatively, if it was created with Save-to-Disk then you can Add Books from directories and it will import each folder as a book record --deriving metadata from the metadata.opf