@gianny,
Currently, adding gallery directories within gallery directories will not create keep the hierarchy.
In a way hierarchy is control by the “album” taxonomy and not the gallery. event if we can scan galleries within galleries we will not be able to know what “album” to assign them to.
This could work if the galleries had the same structure as pages, but they don’t.
You can still keep the hierarchy that you want but you will need to scan each gallery one by one.