Glad I could help 
. But I made a mistake in my first reply about having to create a copy of the vertex array, so I’ve edited that post; I guess I got a bit confused there 
.
Well, on this manual page I read the following:
I guess it was never considered that we might actually want to affect multiple nodes.
Is there in fact a particular reason why you are using the same GeomVertexData for the different Geoms? It is not necessary for adding them to the same GeomNode, after all.
And perhaps you could store vertex indices used by faces in tuples, instead of creating a GeomPrimitive for each face; you could then manipulate the array data of a single GeomTriangles, similar to how you manipulate the GeomVertexData, when removing a face.
Depending on how the vertex indices are ordered, you might even be able to use GeomPrimitive.offsetVertices.