hello Craig,
I don't know HouseCurve app, but from what you wrote ("For the keyboard in my music room app suggests.."), I think you interpret the data wrong. I say that, because I can hardly believe that one would need to reduce low frequencies for keyboard built-in speakers. That would actually mean that you have too much bass, which is very unlikely. And then, I see no adjustments above 3kHz in your chart.
It's just my opinion, but the whole chart looks weird to me. Let me explain what I mean...
At 416Hz you are supposed to increase gain by 10dB and use Q=2.9. Because Q is small, it will affect quite wide frequency range below and above 416Hz -including 757Hz (which in next step, you're supposed to decrease by -5.6dB).
In short, we can't linearize that big fluctuations in such narrow frequency range. Usually we adjust frequency at every octave, or every 2nd octave, i.e. 50Hz, 100Hz, 200Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz and 8000Hz -that covers full audio range.
If we now set gain at 1000Hz and set Q to zero, it will affect all frequencies between 500Hz and 2000Hz (by assuming equalizer does it's job properly). But how do we correct for example 750Hz in this case? We can't do that directly -to do that we would need parametric equalizer. But we can manipulate settings at 500Hz and 1000Hz and this will also affect 750Hz. There will always be small fluctuations.. the idea is to get average flat response.
My additional thought... I think it's not worth to bother making precise EQ adjustments with built-in speakers. Main reason being: they're directed upwards and so we're loosing mid/high frequencies anyway (unless you're listening just above keyboard). What I'm saying is, just set EQ so it sounds to your liking.
Bogdan