Aphetoros:
"Is it working as intended that the glowshroom ladders, etc. aren't usable?"
"Was playing around using it in the otv mod pack so it might be interactions? unsure, just know that the glowshroom ladder doesn't work like a ladder haha "

I think this mod pack is meant: https://www.curseforge.com/minecraft/modpacks/better-minecraft-otv-edition

fixed with one exception:
there is an issue with the combination "vanilla trapdoor on top of a mushroom ladder" -> The trapdoor is not climable (Forge issue: 7775)

will be released in 1.6.0