Quite astonished to read that the only fixes for openGL would be to run in on the CPU instead ! Really ? No other methods ?
Since Apple's OpenGL drivers are deprecated (so they're not going to fix them) and closed-source (so we can't fix them) — no, not really. At least, nothing that would be less work than updating to Metal.
Anyway, one question, before moving Vuo completely to Molten / Vulkan / Metal which I assume will be some work, would it not be possible to test it out for small fixes like these first ?
Not in this case. Meshes are one of those things that you have to do either entirely in OpenGL or entirely in Metal. You can't do a little bit in Metal to work around the problem and keep the rest of the code OpenGL.
I just had a look at Magneson's SVG to XML approach, it's a bust for me (or would take a lot more work and I can't imagine it amounting to anything except an experiment). SVG's parameters for paths include move (M) and curve (C -- provides 6 parameters per point for cubic bezier curve).