I'm not saying that I don't want to use other alternatives, I'm have my concerns about what's gonna happen when:
- I install it on another computer
- I reinstall the operating system
Answered.
BTW, a simple MC Library Backup and Restore after reinstallation will retain all those one by one exceptions, if you were silly enough to use that method. Nothing would be lost.
Naturally, you would have to save a copy of the Library Backup if you are going to reinstall the operating system. Or you could just tell MC to save backups on a disk other than the OS disk. It's a setting: "Options > File Location > Program Files > Library Backups". But of course you have a full PC backup system running, don't you, so that would always contain a copy of your Library Backups?
You can copy a Library Backup zip file to another PC and Restore it to another copy of MC there. Remember, Library Backups don't include the media files. Just the indexing of all media files, and MC settings.
To my if I had the full route of the file in which JRiver stores this information maybe I can create a script that fully loads the exceptions there but I don't know where is that file located,
This way be Dragons! MC Library files aren't editable. There are some tools that you can use to load some data into the Library, but I doubt they include mass loading Auto Import settings. I haven't checked. But don't bother, as this isn't the way to go on this issue. You may have some programming skills, but you would be 100% on your own if you start scripting direct updates into the MC Library.
Bottom line: Your method is a bad idea. You only need it because the file structure you use creates a problem. Fix the cause, as above, move the duplicate mp3 files out of the main directory structure, to a separate top-level directory. Then don't include that top-level directory in Auto Import. Simple.
same about doing a backup, I don't know how, where and which files to save.
Well you have only been using MC for about four days, right? So it's not surprising you haven't learned everything about it yet.
MC automatically creates backups regularly. You can also create them manually.
https://wiki.jriver.com/index.php/Library_Backup