My apologize for never responding. I can't give a reason for why I didn't, but again I am sorry. I have found the reasoning your mod has issues with mine and that is because you add "layer-12" to transport belts. My mod adds "layer-12" to the character along with other collision mask changes to enable hovering over water while also crashing into things it should. I am currently working on an issue for the biggest of problems.
Is there a reason you didn't use layer 11 and 12 instead of 12 and 15? Just curious in case I want to use layer 11 or 13-14.