bumping for good and bad news regarding replays
good news is that after a lot of tinkering i figured out the exact issue as to why the replay seems to desync most of the time, it being that during random small intervals, the replay will be exactly one frame ahead of the actual play session, causing the amount of random calls to desync, making any bullet patterns with random values in them at all completely different.
bad news is that this seems to be an underlying problem stemming from the way GM runs games created in it (possibly related to it not having frameskip, not 100% sure), meaning i'll likely have to overhaul the entire replay system if i want to get it working, dashing all hopes of a quick update. apologies