A glasscutter only creates a scratch in the surface of the glass doesn't it? Then it will not work because you need to score fairly
deep to snap the boards nicely. I guess the cuts need to be about 25% of PCB thickness, and on both sides.
Big difference with normal glass is that the layers of woven glass are isolated by the epoxy filler material, somewhat like
multilayered safety glass. And a glasscutter does not work very well on such safety glass either, I think...
Also, be carefull when snapping the boards regardless of the scoring method, especially after they have been assembled.
Too much warping can easily result in fractures inside components, or in SMT solderjoints.