Unless you call back or email MS you don't know for sure that your request was added to the reservation.
The only way to know if the room assigner was able to grant your request is at check in. Until then, the front desk could give your room to someone else.
You need to check and verify the request. We have had several requests over the years that for some reason never made it to the reservation/resort even though MS said that the request was made by them. I don't know if it was human error or a system issue.