Ok, here's my final free lesson for you: transition frequency is not some descrete limit made of hard rock beyond which room magically stops affecting speaker's response. Beyond transition frequency room still affects speaker response all the way up to app 900-1000Hz, but on a smaller scale than below transition frequency. That region can be corrected based on spatially averaged measurement taken from LP, with filters of wider Q and smaller magnitude.
As for the region above 900-1000Hz, that is not room correction anymore, but a speaker correction. That region can also be corrected, either based on Klippel speaker measurements or, if one is not available for your speaker, you can do it yourself in your room. Speaker should be placed on a stand in the middle of the room, measurement is taken from the distance of 50-100cm and should be gated by app 6-7ms. That should give reasonably reliable response above 900Hz based on which speaker can be corrected.