@Puste Just an idea of a workaround.
You could use Project > Add… > Add New… to create a new script in parallel in your project. Copy the section you want to save then paste the copied section into the new script. Using multiple scripts in one project is usually for multi-axis, but you could use it to store a favorite section for later use. Each axis can be exported as individual funscript files and you can save those and create a library for later use. When you are working on another project later you can use Project > Add… Add Existing… and then copy/paste the section to your main script.
Check out Part 3 at 09:03 - Multi-axis scripting for a tutorial
https://discuss.eroscripts.com/t/how-to-script-in-openfunscripter-video-tutorial/16637