Royal Nepal in C is not that bad - and the pilots are used to landing at altitude in KTM on a rather short runway - unlike TG. But they have a lot of delays and no lounge access. TG sells special fares in C from Ktm - at about 450$ or so round trip - they also may have one-ways. Also worth remembering is Qatar - they fly from Kul to Ktm - but the schedule isn't very good.