However, I think using the maxHeight field on the Door class would work as an alternative way to do the door hack that doesn't require a wacky model file (see the definition of prison_door_metal).
In Grimrock 1 you can't arbitrarily animate objects, every animation has to be attached to a Lever or Button or Monster or Pit or PressurePlate or the like. When you just want to translate something along one axis, Door often gives you better control.
By the way, I'm currently porting the importer/exporter to Blender 2.9x, and have everything done except for fixing one puzzling bug with the game_matrix feature that first started appearing in Blender 2.74. So you might want to hold off on installing ancient versions of Blender and just wait a couple days for me to fix that.