I’ve had Sense (which we fondly call “non-sense”) for many months, and it’s still hot found most of our all-electric home properly. So, getting weird readings from it is exactly what I’d expect.
Regarding heat-pumps, we have a 5 ton (60,000 rated BTU) Climate Master heat pump, which is slightly less than the combination of your two. It provides heating and cooling, depending on what mode we have it set for. Both Sense and my WelServer show the heat pump draw at about 4,900 watts. We also have a boost for when the heat pump needs some extra assistance…fortunately not that often…resistance heating is about the least efficient/most costly heat you can get.
My system draws 4.7 KW when the heat pump is running and 6.3 KW when the booster kicks in. So, that means that I’m getting most of required BTW for something like 1/4 the electricity cost and the remaining BTU at 1x efficiency.
Unit Power Draw Conversion Rated BTU
Heat Pump 4.9 KW 12,000 58,800
Resistance 1.6 KW 3,412 5,459
So, I believe that you are seeing about the correct heat pump draw. The only benefit of the resistance heating is that the response time is quicker, which is why it kicks on only when the temperature is very different, runs for a short time, then turns off again.
I’m surprised your HVAC guys can’t explain what your system is doing, because what you describe matches my understanding of how such systems work. Basically, since a heat pump is about 5x more efficient than electrical resistance heating, the objective is to use the heat pump for the bulk of the load and only trigger the (much smaller) booster heating when absolutely needed.