Here's another bug in RPG_RT 2k3 similar to #2156 ❗ In particular, I tested this with dynrpg version.
Make an event on map 6
Var[1] = This Event MapId
ChangeEventLocation(x, y)
Var[2] = This Event MapId
Msg: "\v[0] \v[1]"
Result: "6 0"
This also occurs with "SwapEventLocations" command. Both of these commands hard code the map id to 0. This was consistent in 2k (every event always has map id 0), but is now inconsistent as they tried to fix this in 2k3 but fell short here.
Unfortunately, we'll need to emulate this bug for correctness.