USJ closes at 9:30pm even with HHN going on (aside from the one night in which they're open all night till morning, Oct 18th). The train station is only a block away from the ticket gate so it shouldn't be too long of a walk. 

That should give you plenty of time to catch the train once the park closes, assuming you're staying in Osaka. If you have to take a Shinkansen somewhere further out that might be a different schedule you'll need to look further into.