Within a default program, you can nest Email Programs; within an Engagement Program you can nest a variety of program types. However, with Email programs, if you attempt to send an email located in an email program from a smart campaign in the main program, the sent email does not inherit the tokens from the enclosing email program.
I have confirmed this behaivor with email programs nested within default or event programs. I assume the behavior is the same with emails sent by the engagement engine.
Please allow emails sent from a parent program to inherit the local tokens set on the enclosing email program or other nested program.