Fedor Koleganov

Disableself and disableexternal do work per point of the object, you can see it if you assign the value of 1 to let's say just a part of the patch. However points with the value of 1 will both ignore and be ignored by the points with value of 0 when resolving self collisions which in Vellum's case collisions between all points of the same Vellum Object (unless those points are grains or fluid, those are handled differently). If collisiongroup and collisionignore work, use them.
Also, if you end up using SDF volume colliders for external collisions, those only consider the collisiongroup and collisionignore attributes, disableexternal doesn't do anything for those.

You can Merge SOP sphere geometry and convert to VDB with VDB from Polygons SOP. Then have plug it as a second input to your Group SOP and change Bounding Type to Bounding Volume.

Another option could be to use Find Node window, press Ctrl+F in the Network View, there you can find nodes by what value the parameter contains.