Videospirit I mean it sounds like the bug would be triggered from a badly timed manual press when the ordeal of the claw map is first loading too, not just doors/stairs.
As it stands in the public build, yes it would. The modified version I made for ER247 above modifies the party change script so that it doesn't process the button press unless the player has control of the party and no other event is in process. The problem with doors and stairs is that if you press "W" and the direction button that gets you to use the map's "warp point" more or less simultaneously, it triggers both events. So the only way to stop this from happening is to define certain areas of the map, adjacent to these map features as places where the player can't use party change.
I thought I would have to write a script enumerating every map coordinate in a function called to check if the player coordinates were at such a location, but then I realized while writing this that I am a moron. It's just a matter of defining a region on the appropriate map spaces. And I've just done it.
ER247 I doesn't crash nor changes the team constantly unlike before
One last clarification. You didn't mention changing the team constantly in your original report. Am I correct in assuming that happened with the modified game version I gave you? If so, I'd again suggest looking at the calibration on that controller.