The problem with the building modifiers is that some of them are intended for specific holdings, eg nomad/family palace/hospital/trade post and the wiki doesn't clarify which.
Building cost/time modifiers need to be applied to the province or character (I think)
So it's not an error, you're justing using them in the wrong place (which isn't clear from the wiki)
A work around is to use a recurring event to add a province modifier if the building is present (I don't think they work as a holding modifier)
Building cost/time modifiers need to be applied to the province or character (I think)
So it's not an error, you're justing using them in the wrong place (which isn't clear from the wiki)
A work around is to use a recurring event to add a province modifier if the building is present (I don't think they work as a holding modifier)