That Parent error happens even in vanilla, and (if I recall correctly) its related to 2 blocks occupying the same space, with one being invisible. It probably doesn't have anything to do with that particular model, it can happen on world gen where terrain decos collide with invisi world blocks. I can be solved by taking a rocket launcher and blowing up the colliding blocks. The bigdecoration radius might need increasing abit, not sure if that might help on spawning. I can look back at the unity model if needed, but I think its fine.