Hi,
I would like to point out that the tag leisure=horse_riding should not really be used to tag specific buildings, but should be used for complete riding facilities. For riding halls we have the tag building=riding_hall. See also:
https://wiki.openstreetmap.org/wiki/How_to_map_a#Riding_centre_(equestrian)
https://wiki.openstreetmap.org/wiki/Tag:building=riding_hall
https://www.openstreetmap.org/way/566123394#map=16/51.74947/4.39269&layers=P (example)
If the outline of the riding centre is not known, then it can be mapped as a node instead of an area.