Yep I am pretty sure they will not be preforming on those days. Unless there is a really late or early show, but I doubt it. Epic Theatre holds 2000 people, making it a good venue for the Wiggles. There is only 2 bigger theatres at MGM, The Action! Stunt Show and Fantasmic's Hollywood Hills Ampitheatre.
The LMAX show is too new to close for the day for the wiggles, and Fantasmic doesn't have a cover over it, so the show will be at Indy's place for a few days.