If you are going to continue to post on speakers topic I strongly suggest you at least read Toole's book otherwise your posts will look like spam.
Once again, for all of you who missed it, here is a summary of 2 pages that he wrote in 500 pages book about the distortion:
"In loudspeakers it is fortunate that distortion is something that normally
does not become obvious until devices are driven close to or into some limiting
condition. In large-venue professional devices, this is a situation that can occur
frequently. In the general population of consumer loudspeakers, it has been very
rare for distortion to be identifi ed as a factor in the overall subjective ratings.
This is not because distortion is not there or is not measurable, but it is low
enough that it is not an obvious factor in judgments of sound quality at normal
foreground listening levels."
And one more thing: waterfall plot will not help you identify non-minimal phase issues - it will help you identify room resonances.
More info in REW help:
https://www.roomeqwizard.com/help/help_en-GB/html/graph_waterfall.html