You said in comments "Any plan add merge block issue finder?", is that what this topic is about? Because you're not really saying why you're telling me all this =)

There's already such a feature (prints in mergeblock's terminal) but it's not gonna tell you exactly what block is the problem, I'd have to clone even more code from mergeblock to identify...
It's also supposed to blink the emissive yellow.

Why do you even need so much detail on that btw? You seem to know the problem, so I'm confused xD

Also the game supposedly also says mergeblock can't merge if you're in a cockpit in one of the grids, maybe ask keen to also print it to nearby friendly players' HUD.

As far as i know KEEN use very messy trick to merge piston/rotor head.
Before Warfare2 Piston had issue that you cannot merge when in full down position.

As you may know that piston Head is full block and body is 3 blocks while head is inside that 3 body blocks == "Cannot merge some blocks occupy same place".

I made example for KEEN and they see that.... as now that "issue" in my BP is fixed.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2440733407

Also "this one" work after WF2 update but if i spawn it near cliff it will be broken.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1832754042

I suspect that head of Rotor block will merge somewhere around rotor like block next to it,
Just to trick SE block_based_system that rotor head on piston can be merged but not in single line.

I just want to know what "Air block" will be considered as spot for Piston/Rotor head block on merge event

I also suspect that something is wrong with <MountPoints> in blocks.
After few try and error i noticed that vanilla catwalk no longer unmerge if is touching sloped armour (By block space). _/I

That is why i like to know faster what block is the issue.