You have the trough because the waves in the specific room at the specific frequency are canceling each other out. You can’t really change this for low frequencies by pumping more energy into it. Your amp and speaker cones will work really hard until they might stop working.
You are trying to fill nearly 10 dB which means twice the volume and ~8 times as much required amp power at this frequency.
This is not about that. You are not yet at the stage of Roon using the convolution filter. You are just configuring the correction values that HC should use.
You can configure HC to automatically fill a maximum trough of, say, -5dB and not more. Or alternatively you can tell HC to allow only cuts so that all corrections are reductions of volume.
This is in the HC manual on Equalize Setup - HouseCurve
This happens when it doesn’t get a good reading during sweeps. E.g., if volume too low or environmental noise:
By the way there is a dedicated HC thread where all of this and more has been discussed, and where the HC author is present: