Bumpers can be crafted only using default:wood. I think, there should be
There is a recipe in moreblocks (version from git.bananach.space) to
craft default wood from any wood, so I think it's still important to
change that advtrains recipe, but there is a useable workaround.
W _ _
W _ _ -> 2x default:wood
_ _ _
W = any item from the group:wood