@Hannes_Kerschbaumer
There is not jet (very unfortunately) the functionality of adding jumpbar aliases, nor Dorico key commands to scripts. You can currently launch them only through the menu or clicking on the result after a jumpbar search.
If you are on MacoOS you can easily assign a shortcut for your custom scripts, via Keyboard>Keyboard Shortcuts>App shortcuts… in System Settings. It works great!
(At the beginning of this post you see a screenshot:)
If you need to reuse the same scripts many times in a row, the jumpobar remembers the last shortcut, so you need to click only “J Enter” to repeat the last scrip. Or assign a shortcut to the Key Command Run Last Script.