I've tried modifying the file itself and I honestly can't even find where the bounding or collision boxes are. There's that 1 2 9 at the top then the 1 followed by 2 points which seems to affect collisions but then it's not collisions or something because it just describes a single box from 0, 0, 0 to 1, 2, 9 but the collision shape is more complex than that and works just fine until I try to modify those values which breaks the collision but does nothing to the bounding box. I look in the .blb for the open coffin and it has a more complex bounding box or collision or whatever that list of boxes is so I try to recreate similar boxes on mine and no matter what I do it just breaks the collisions and does nothing with the bounding boxes. I try to fix it with that brick grid stuff in that blb format thread and it just results in a completely nonworking brick, so I have no idea what I'm doing wrong with this nor why I can't seem to figure out what's going on or what I'm doing that's different from what other people's accounts of what they're doing or descriptions of what I should be doing. So, a bit of clear advice would be nice.
EDIT: OK I had COLLISIONs deselected when exporting so that settles that problem and the 2 collision boxes do appear at the top now, but the places where I can build on/in to are still wrong and I don't see what's different between my file and the open coffin file that you can build in to.
EDIT2: Finally got it working. I had to change SPECIALBRICK to SPECIAL and it's fine now. That's lretty obscure and not really clearly documented anywhere.