Wow! I am also very surprised about the results.
... and I love to speculate. So here is my speculation on "WTF happened there?"
The first thing I noticed is that a manufacturer whose cheapest product costs $10k uses a $300 measurement system for its PR measurements.
From the manual:
View attachment 122366
I have nothing at all against Dayton's measurement system, it's a great overall package. However, nowhere in the manual is a description of how to make reliable two-channel measurements with this system.
Something like this:
View attachment 122370
Without this, possible frequency response and phase errors of the measurement amplifier (and audio interface) are not compensated - which is a possible source of error in loudspeaker development. For professional work, therefore, other systems are usually used.
But there are bright spots, namely that SoundStage's measurements are very likely correct.
If you take the on and off-axis measurements given by HeavenlySoundworks in the manual and scale them to fit the SoundStage measurements, they are almost identical except for the smoothing.
View attachment 122373
It just seems that HeavenlySoundworks is not able to make gated measurements and therefore works with 1/1oct smoothing and truncates the measurements at 700Hz to hide possible room resonances.
The HeavenlySoundworks owners are certainly not going to heaven.