Concerned with Nulls vs Peaks-Acoustics Forum-Acoustic Fields Forum

I have been sweeping sine in my room during the process of reflection management. I’m pretty happy with my reflection absorption and diffusion of mid-high range (well, at least for the barrier I must deal with). So far I got rid of the flutter echoes which caused me to start improving my room in the first place and the pinging off the ceiling is gone too. I didn’t make a move until I was confident with my knowledge. Its a good start.
And now I’m tackling bass management. Oh gawd. After months of researching, yesterday I finally started to apply what I believe is the best approach.

My concern/question is: during my sine sweeps I have noted particular frequencies that cancel and a few small ranges of frequencies that attenuate. This all of course happens at 500hz and under.

Now, I have taken an FFT trace using Room Eq Wizard and although I am still learning it I believe the trace to be calibrated correctly because it verifies what my sine sweeps are telling my ears, I think.
My question is: would a cancellation be referred to in a trace by an adjacent peak?
Ex. Would a 150-176 attenuation ( verified by ears by hand swept sine) be visually referred to in the simple frequency range window by a neighboring 180- 200hz peak?

Perhaps a trace will not isolate, visually, an attenuation? Or is there another window I should analyze? I need to learn how to read the waterfall.

Any comments on ‘cancellations’ or ‘attenuations’ are appreciated.