The Block Conditions for Recipes was changed to CraftTweaker conditions a while back.

The wiki shows a few examples for this condition, but not for blocks.

https://github.com/CleanroomMC/Multiblocked/wiki/CraftTweaker-RecipeBuilder#recipe-conditions

I am trying to learn how to use this mod properly (like limiting recipes to number of layer repeats a block has), but I seem to need the block condition for this.

Last time I touched this feature was in this post, but I was unaware of the full switch to CraftTweaker conditions until I tried to use this condition.

I've appended it to the wiki, thank you for notifying!