None of them are on TPE mind, TPE is more a regional service anyway nowadays and always has been. It's never been intercity.
Personally for Sunderland I'd be pushing for something more like:
With Metro extensions through to Seaham and Dalton Park both every 20 minutes combining to form the current green line. Then the South Hylton branch is replaced with an extended line onto the leamside line with 3 services each 30 minutes running Newcastle - Durham and beyond, Sunderland - Durham and beyond and Sunderland to Newcastle combining to give a 15 minute South Hylton to Sunderland, 15 minute Newcastle to Washington and 15 minute Houghton to Durham. The beyond being Darlington, maybe a TPE service which currently ends in York or whatever. It would pretty much connect everything up and most of Sunderland bar the North side would be 15 minute walk to a Metro or rail service.
Our LA's are too short sighted though and see the Metro as the be all for everything tho hence the utterly stupid ideas like a 10 minute Sunderland to Newcastle service via Washington. It also sorts the doubling back problem out.