Currently the only supported auto option is auto and optionally suffixed with -start and -end. Is it possible to have something like auto-bottom? I imagine -left and -right would be nice as well. Maybe Blueprint is limited by the Popper.js library?
This is a limitation of the Popper.js library.
I think the closest you can get is to set your desired position instead of using auto and then rely on modifiers to flip or reposition the popover if your desired position is not possible.