Hey there! I could use some help from you guys.
Do you know if its possible to change colors of a specific slab-type?
Lets say i built all my costum building roofs with red slabs and didnt use them anywhere else. Now i decide that red doesnt fit the village look anymore and i want all those red slabs to be replaced with blue ones. Is there any relatively easy way to manipulate the saves or the game to make all these red slabs blue?
Im not a modder myself, so go easy on me pls 
I don’t think it would be possible to modify the save game in that way. Your best bet would likely be to save the building as a template, modify the template, and then remove and rebuild. Not an ideal solution, but you are very likely to break things if you try to modify a save.
We need a “Painter” class 
or someone who can mix up some paint and we can have the workers paint to your hearts content 
Mwa, you can simply save the building like @jomaxro said and destroy the old one, build a new one