Sorry, it seems you simply repurpose the one "obj_tile_wall" instance, repositioning it as necessary.
Please do comment if I've misunderstood this.
Are the created "obj_tile_wall" instanced cleaned up again somewhere? (I assume that on larger levels the number of created instances could still become substantial?)
I can't seem to find code for this in the "tile_meeting_precise" script.
To be sure I've incorporated an alarm[0] in the "obj_tile_wall" object itself, which destroys it after a number of frames.
I look forward to your thoughts!