I've taken the Capitol Ltd a few times from Cumberland to Pittsburgh, and it's been late each time. Once really late (like 1:30 am into PGH). So check for updates frequently. I think AMTRAK has an automated text notification thing you could sign up for.
AMTRAK doesn't own the lines, and is at the mercy of the freight trains that use the lines (I think CSX handles dispatch). So they get low priority, unfortunately.