Odd-shaped room

I can't quite figure out the inside dims of the rooms. Dims in feet would help us yanks (or at least for the metrically challenged ones like me:)

To get a rough idea of the modal response, use the average distance of the skewed wall. Your calcs should give you the same square area measurement. Whatever it is, if that's what your room is, you can't do much about modes anyway. So dont worry too much about the room modes and just use enough absorption to eliminate the peaks and nulls.

I would consider the skewed walls to be the rear walls of your rooms. Full absorption on rear wall and treat the vertical corners as bass traps as well as all the other corners (12 total) you can trap. If you choose diffusion for the rear, that can be in front of the absorption.

I'll also mention you also should use RFZ absorbers on the side walls and ceiling. Carpet or rug can be used for RFZ on the floor too.

All the above is standard stuff but as you will note from other threads on this forum, (You are following the other threads too, aren't you?) a cycle of acoustic measuring, analyzing and adding and/or tweaking panel placement is usually necessary to achieve the best results.