I have another bigger and better mod: https://mcreator.net/modification/82889/jolium-mod
The new version fixed all major bugs.
This mod adds levels 0-11, 13, and 3999. It takes a new perspective on backrooms mods focusing on building and exploration rather than survival. There are many new craftable building blocks in the mod however the portal can't currently be accessed in survival.
You can teleport to and from the backrooms using the no-clipper.