Yeah I think there are engine limitations with the latter, if you mean something like each style having a different language assignment. Not having the resources of a major software company, building our own spell check engine and such isn’t really feasible.
For numbering though, you can indeed do that. It’s a matter of going into the Styles compile format pane, adding a matching style to the list so that the compiler can modify it, and then putting the numbering system into the prefix or suffix field for that style. Here is a detailed how-to for creating numbered paragraphs in the margin.
As Katherine notes though, you need something a lot closer to the end product to have numbering in the editor. Scrivener can compile 72 of 182 documents from the Draft folder, on details as transient as word matches in the document as you type. It would take a lot of computational power to keep that going “live” while you write.