The room can be fixed later in the time, some people just don't like reselling speakers and don't want to invest in the room as they are going to move, etc. But this is true, of course, room is maybe even more important than the speakers.
Figure out how exactly? There are no detailed measurements existing. And when there is, then it doesn't look convincing.
There is no ground to even make some theory.
Yours actually look better (well I don't really know because nothing higher than 5 khz included for some reason).
I'd prefer higher resolution and some frequencies higher than 5 khz included.
Are ATCs V-shaped in general? Yours have some bass boost and what is in higher frequencies?
That small...
There was also a second model (active, not sure if discontinued) measured and it was "iffy" too.
So unless proven otherwise we can assume they are all "iffy".
But IMD increases as you increase driver operating range? It's one of the reasons multiple-way loudspeakers exist.
More frequencies to play = more IMD.
Anyway IMD and even THD of ATC loudspeakers are a mystery.