Why is the values list empty?
https://github.com/Vazkii/Quark/blob/master/src/main/resources/data/forge/tags/blocks/wg_stone.json

If I do this for the stone variants of my mod, they are not integrated into the strata layer system of the mod TerraForged.
And if a stone variant of your mod is disabled it also doesn't generate as strata layer while mine still does. Has that something to do with each other?

The tag values are added dynamically:
https://github.com/Vazkii/Quark/blob/master/src/main/java/vazkii/quark/world/module/NewStoneTypesModule.java#L82-L103