I'd start by solving one issue at a time. If LaunchBox is stuck continuously scanning or updating ROMs, let that problem get resolved before updating RetroArch cores or changing your RocketLauncher setup.
If everything is currently working with RocketLauncher, I wouldn't update anything until you have a backup of your LaunchBox folder and configuration files. Newer RetroArch cores are generally safe, but if RocketLauncher relies on specific emulator paths or versions, updating without a backup could introduce new issues.
For the endless import/update process, check whether LaunchBox is monitoring a folder that no longer exists or contains a huge number of files. That can sometimes cause it to appear stuck. A backup first, then troubleshoot each issue individually, is the safest approach.