If they are using backups on their simulators/​computers, they just restart from the last backup. Therefore if the root universe is using backups and all simulated are copy from the root, the system is stable.
The restart is not visible inside the simulated universe.
Matrioshka universe is not stable because glitch on any level will terminate downlevel
If they are using backups on their simulators/​computers, they just restart from the last backup. Therefore if the root universe is using backups and all simulated are copy from the root, the system is stable. The restart is not visible inside the simulated universe.