The "clear" answer to the question is:
Each and every attraction that is listed as being a part of Evening EMH at the Epcot theme-park at Walt Disney World, will stay open until approximately Midnight in the eastern time zone.
If, on occassion, Illuminations is scheduled for a 9:30 PM Eastern time presentation and the Epcot theme-park is scheduled to close at 9:30pm Eastern time, then each and every attraction that is listed as being a part of Evening EMH at the Epcot theme-park at Walt Disney World, will stay open until approximately 12:30 AM (in the morning) in the eastern time zone.
This includes each and every attraction in Future World that is listed as being a part of Evening EMH at Epcot.
This includes each and every attraction in World Showcase that is listed as being a part of Evening EMH at Epcot.
On various dates, there will be certain other attractions that may be open during EMH as well.
The American Adventure in World Showcase is scheduled to have only a limited number of performances when it is a part of Evening EMH at Epcot.
You need to check with the "Times Guide" handout (that is available at many locations around Epcot) to make sure that you arrive in time to see one of these shows, if you intend on viewing it during Evening EMH.