You have to just look at the agency is that the use. If you were a partner agency you’re on Momondo. Future.Travel, is located in Asia. Momondo is European focused. Therefore you will not find all agencies on Momondo.
Like every meta engine, you’re not gonna get the lowest price ehen they leave out key agencies, or show you the best price for them as compared to the best price for you.
You’re better off to find a full service travel agency or OTA that you’re happy with and have them do the searching for you.