What version of More Mystcraft are you using?
0.5.3

What version of Mystcraft are you using?
0.13.7.02

What version of Forge are you using?
14.23.5.2820

What version of Minecraft are you using?
1.12.2

What modpack and modpack version are you using, if any?
Garternay 1.1.1 (Optifine Excluded)
However, this does occur in an a clean environment with only Mystcraft + More Mystcraft installed.

Does the bug occur server-side, client-side, or both?
Both

Describe the bug
The "Double/Full/Half/Zero Cloud Height" modifier pages do not seem to affect any ages generated using them. The clouds render at y-level 127, (or lower in the case of Skylands Ages) regardless of the modifier used.

Thanks for pointing this out. It has been fixed and cloud height symbols will be fully functional in the next release.