You're facing 56 around a table. I think 64 is a different colour as it's a priority (extra legroom) seat.

These trains aren't compulsory-reservation, though. Most train companies don't really care where you sit (as long as you're not poaching somebody else's seat) but I don't know what TPE are like (anyone?) Reserved seats will have a card slotted into the seat back (or a little digital display by the luggage rack - on Pendolinos, for example) telling you what stretches they're reserved on.

If it's a weekend, I think you can also upgrade to 1st class, on board, for £10.