It's at H-9 alright. But in the UPPER half of Windurst Waters, not the lower half. Run up to the H-6/I-6 area from lower Windy Waters to be presented with the new coordinates from the upper half.
She sells Tarutaru Folding Screen as well, not too sure if it's Conquest standing related, however. I believe the cost was around 3100~3200 at rank 8 fame.
Windy Waters used to be just one map, so that location was most likely correct at the time. SE has since split it into two maps, so thanks for the right location it should be updated.