I went to review the technical document Wolfram-ModelsForPhysics.pdf, and for the "formal system where could be multiple rulial spaces", I didn't see that. Well, I am not deep in Rulliad but below is how I think. And please forget about my previous "Computational Equivalence", I mistook that concept.

Yes, "Rulliad contains all possible computational rules", but do you remember that hypergraph? Rulliad contains rules only about edges on nodes: nodes that have no inner attributes, nodes that are only distinguishible by their connections in the directed (multi) graph

so rules are about how those edges change, regardless of nodes themselves. There may be different sets of rules with different input/output edge groups, but by difinition Rulliad includes all of them, I didn't see where the other Rulliad are.

By the way, I don't know why but I have a one day cool down after I post or reply, so I didn't reply until now.

It's about computational equivalence, different computational rules can have the same rule signature, being computationally equivalent, which can be seen as the same rule. In my opinion.