Imo the Cornscalas are in the right ballpark for this type of room.
Ime for difficult or unusual rooms, you want speakers where the radiation pattern is not too wide - say 90 degrees over most of the spectrum - and where the off-axis response tracks the on-axis response fairly well. This way whatever energy the room bounces back at you, it supports the direct sound from the speakers rather than fighting against it. This implies large (and in particular broad) speakers, because it takes a large source to maintain good directional control well down into the midrange.
If the low end is problematic, like if it is weak or boomy or whatever, that would need to be diagnosed and dealt with.
Are the speakers going to be in front of the floor-to-ceiling windows? If so, then we might not want them to be any bigger than they need to be, to minimize their impact on the view out the windows.
Hope some of this is useful.
Duke
dealer/manufacturer