Alright, after a bit of trying to figure out what the issue really was, I found out that the crashing came from the amount of loot around the map, which was over 800 bags + 70 from overdrill (HOLY SHIT).
Also, ignore the heist icon and name, just a BeardLib Editor thing.
Now, onto the heist...
I decided to reduce the amount to just 91 bags of gold, previously over 500, also don't do overdrill because the bag limit is 120, and I added just 6 more money bags. In total, it's 97* bonus bags with the standard 14 bags offered by the Vanilla version. Might as well add a bit more and increase the bag limit if the game won't crash when players load into the heist.
And if more crashes happen, I'll completely trash the idea of an edited FWB and go for other heists like Beneath the Mountain, Big Bank, San Martin or whatever I wanna do, just gotta make sure not to add over 200 bags in any of the heists that I'll edit.
Please tell me if you're experiencing any crashes, I'll get a fixed version.