It does work. The likely problem is that the person is trying to use Chisel mod with Geostrata COBBLE instead of smelting the cobble first and using the regular "stone" blocks in Chisel.
I used Chisel mod to convert about 8000 Geostrata limestone blocks into Emasher limestone so I could make slickwater with it. But I had to smelt all 8000 blocks first before Chisel-ing.
Also, Geostrata Opal is such a great building block, especially when you can create so many variations in the crafting table. My base looks great, really happy with Geostrata now and glad I didn't turn it off in Monster!