Welcome to our forums, qeliou!
We regret that your request was overlooked, but let's try to finally find a solution to your problem.
First of all, the files of your installation are heavily modified, not to mention that the files of dubious origin that it contains, such as gtasalauncher.exe, can install potentially unwanted programs (PUPs) and access your personal information.
These modifications and files of dubious origin are not ideal for using Multi Theft Auto and may lead to unexpected results such as crashes, missing gameplay content or performance degradation. To restore the health of the installation and completely remove unnecessary files, obtain it from Rockstar Games and reinstall it, and run an anti-malware software at your own discretion (highly recommended).
In the future, if you wish to play with San Andreas Multiplayer, consider creating a separate copy of your installation so it doesn't pollute the installation directory. If you skip this step, you won't notice any changes, because Multi Theft Auto can ignore files that would modify the game's operation and aren't necessary to run it.
If these steps above didn't solve your problem, run MTADiag again after the reinstallation and feel free to let us know!