I had a quick question regarding how many scenarios are included with Return to Night of the Zealot. Everything I can find about the set says it updates the original 3 scenarios, but on the rules sheet, it says that "Each of these new scenario cards is included in one of the following encounter sets and enhances the original scenario" and then lists the 3 "Return to" scenario sets as well as "Cult of Umôrdhoth (new)". I only received scenario cards for the three "Return to", was there supposed to be a fourth scenario included, or is that just referring to the three new cultist cards?

It's just referring to the new cultist cards.

The Return to... sets are intended to jazz up existing scenarios. They don't seem intended to add new scenarios.

Yes. It has 4 new & 2 replacement encounter sets, but only the 3 scenarios.