I not know anything about new trails being made at Cwmcarn.
But there is plenty natural trails around that area to fill a good few days, so def never a reason to do 2 laps ... well, not unless you really wanted to.
There is a new website for people riding around that area to meet up. The guy who owns the site may try to pressure you into paying a £20 membership
...just ignore him ... but just turn up on one of the locally advertised rides. I pretty sure the guys who do the actual riding wont care in slightest if you payed membership or not ... and they will show you some nice trails.
Halfway mtb