Slitherine

(Japanese) snipers behave much like recon units, they are supply immune and can't change hex ownership.
Unless they hop on a train, then they are able to change ownership.
This can't be intended.

I often use sniper units as garrisons for other factions than Japanese.
This Indian fellow entrained at Pyu and moved south leaving a trail of British hexes.

The 6Kampinoska map of your GC gave me the hint that AI trains love to capture unoccupied towns of mine. I immediately gave trains the noCapture trait.