I'm not sure the first graph you posted shows 'no smoothing'. I would expect the graph to become more jagged as you go higher up the frequencies.
In your post 7, considering the asymmetrical nature of your room, both your speakers seem to have a very similar frequency response (FR). Are you sure you didn't have sound from both speakers when you did both measurements.
Anyway, I suggest you concentrate your measurements on the 0-500Hz region. You can do this on REW. To measure the left speaker only, I suggest you firstly get the REW signal to come only from the left speaker, and then place the microphone pointing directly at the left speaker from your listening position and placing it where your left ear would be. Do the same for the right speaker.
When looking at the FR graph use 'no smoothing' and the smallest range of parameters on the two graph axis that will include all the peaks and dips.
The big dip in your first graph is likely a room mode:
https://amcoustics.com/articles/roommodes
If you can move your speakers and listening chair about you might be able to improve things but it won't be perfect. If you can use room treatment that too would help.
Do you have DSP or EQ equipment?