Yes, you'll only get feedback if
1) you book through AW
2) the escort leaves you some
Even if you do 1), 2) is not guaranteed. However, if you leave the escort some feedback they'll often leave reciprocate as a courtesy.
Were the WGs you saw recently and advertised on AW? If yes, try contacting them and say you had a nice time (that is if you actually did!) and will make a fake booking. If they agree, make the booking, leave feedback and wait for theirs. This is the simplest solution unless you want to make more bookings just for the sake of feedback.
Some WGs who expect feedback before accepting a booking may still agree if you contact them and explain the situation. After all, everybody starts with zero feedback but they may be wary that an unknown person is a security risk.