I think they will be fine. The Sabrina needs boundary reinforcement to get low bass the the 1’ off the back wall might even help. 24” (from the driver) would be better and enough imo.
in my second system I have a pair of Thiel 2.4s (same size as the Sabrina)in an even larger room than yours and they shake the walls with bass. It is about how far you sit from them. Try to get them closer together 10’ or less and sit as close as possible for tue room.