It might, but IME it often takes a week or so before yield management release more seats into the discount booking classes. Amazing how flights that were R0 V0 N0 suddenly go to R9 V9 N9 when the sale fares are no longer valid.

BTW, Expertflyer also draws on US market availability, IIRC. The thing about all those tools (also KVS, ITN etc) is that they're fascinating until you really need them, and you really need them when you're chasing the last sale seats around - which is exactly the time when differential market availability is most likely to be very pronounced.