If you used a tube glue like Testor's red label, it was a solvent glue with a plasticiser filler which slowed down evaporation and helped fill seams at the same time (not very well), it may work by freezing.
Superglues (CA) work great in tension but are lousy in shear. Are you old enough to remember the guy hanging by his helmet from the overhead beam. Not falling, but if you smacked the helmet on its side the bond would break. You won't easily pull a CA joint apart, but if youi can impart a shear or twist the parts will likely separate. CA debonders may work but are a hazard to the plastic surface - causing hazing and distortion.
True solvent glues; Tenax, Tamiya Green Top, MEK, Lacquer Thinner, and the like work by welding the two sides of the seam into a solid piece. Just like welding two pieces of steel, they won't separate easily. Perhaps resorting to cutting. More lacquer thinner may help soften a weld but the surface is hazarded like CA debonder.
Speaking of cutting, use a European razor saw to cut the pieces apart . The saw is very thin. Drag a corner along the joint until you have a kerf started then saw carefully to separate the pieces. The problem here is you will loose locating pins - but they would likely be compromised by most of these methods.