I'm using the mesh boolean geometry node in difference mode. Was expecting it to cut like a the modifier but alas not. Getting the above strange results where some of the geometry that ought to be cut is instead added.
Both objects in the boolean are generated from the curve to mesh node. All of the geometric data being used is both shade smooth and realized mesh geometry as I'd read that it not being so can cause some issues, but no dice on those being useful. I've also tried merging the "object doing the cutting" with a merge by distance node before the mesh boolean in-case there was some non-manifold shenanigans I wasn't cogniscient of, but that did not fix it either.
Delete geometry node doesn't really work as a workaround as it doesn't create the nice triangular cutouts I'm looking for nor can I work out how one could procedurally reshape the geometry from bad blocky delete geometry node cutouts to nice triangular cuts.
So I'm at a bit of a loosend as to how to proceed, anyone got ideas?