One of the simplifications that's going to be included in the simplified version is consolidating painted woods into conjured tree wood, conjured fungal wood, conjured berry wood, conjured fruit wood, conjured root wood and conjured grain wood, with some allowances for the more valuable materials like sunberries and golden apples. This is more to make noble demands more achievable, though. If I did stone painting, I'd definitely simplify painted stone, probably into sedimentary, igneous, metamorphic and ore(for value purposes). The magma safety issue would be the main problem, the way to solve it is to have a more pleasing way to say "blue painted magma-safe igneous stone". That way stones only need eight painted materials.
The number of materials really is the problem, not the 16 reactions. Looking at the definitions for stones, though, I have an idea:
[INORGANIC:SANDSTONE]
[USE_MATERIAL_TEMPLATE:STONE_TEMPLATE]
[STATE_NAME_ADJ:ALL_SOLID:sandstone][DISPLAY_COLOR:6:7:0][TILE:'#']
[SEDIMENTARY][AQUIFER][SEDIMENTARY_OCEAN_SHALLOW]
[IS_STONE]
[MELTING_POINT:12070]
If someone used find and replace to change "[INORGANIC:" to "[INORGANIC:BLUE_" and then "[ALL_SOLID:" to "[ALL_SOLID:blue ", all they'd have to do is cut out the code that places it in the world and splice in the colours, and do all that 15 more times. It's still a long and tiresome job, and the complexity it adds is a bit much even for traditional MLF. I've already been thinking about having an "ornate" version that includes things like the divided realms royalty in the united castes, so if someone wants to do it, I could put it in there. I'll add generic conjured stones along the lines of cloudstone, sunstone, moonstone at some point, I'll put it into long term plans. I'll make them fairly light so they don't make stone fall traps too powerful.