If it is under the Disney umbrella, I’d bet that Disney World, Disney Springs, the Raglan Road Irish Pub, and Disney+ are all legally separate companies.

Probably, but is a customer expected to know that? What if you're inside Disney World itself and you're injured on the It's a Small World ride, and then Disney says "oh, that's not us, that's owned and operated by 'It's A Small World LLC'".

Part of the attraction of the whole Disney Springs area is that it's under the Disney umbrella. As a visitor, you know that the company is going to keep everything clean, make sure that everything is up to high standards, etc. You're probably going to pay a bit more to go to a store / restaurant there than a typical strip mall, but in exchange you get part of the Disney experience. It's pretty reasonable to assume that that will also include restaurants that produce high quality food and that ensure that someone's allergy needs are met.