After a weekend of hard work I mounted another 35cm of Rockwool on my front wall. Think I'm getting there. Got 10dB more between 60-70Hz + some other improvements. THAT made a difference to the sound!
The peak at 120-140Hz is probably fixed by hanging a final (hope so anyway
) absorber in the ceiling. (BTW, still Genelec 1030A speakers w -4dB treble tilt)