Max, that is really great you seem to have found a way to tame HRM on the UHK (like Achordion for QMK and similar settings for Kanata allow).
I personally did not took the time to replicate your approach on my UHK, because it seems quite involved and I do not have the urgent need for it. In my approach I use the HRM on the bottom row, where I do not get any wrong triggers. I got not many, but a few while testing them on the home-row. But for my layout the bottom row is a great place, still I see that the home-row itself is surely super interesting, when one gets it working without any problems and wrong triggers.
I see your work as a solution if one is really urgently wanting to get HRM working on the UHK. The relatively complicated setup is likely the reason that there is not so much feedback to your cool solution. For many it is likely more a proof of concept and should be integrated into the firmware and be exposed in such a way in Agent that one can set a few switches or general parameters to fine-tune the HRM for personal use.
That brings me to a few questions to ask to you – as now being or becoming the master of HRM 
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Are you completely free of getting wrong triggers or having any downsides (fast and slow typing or just lingering with your keys on the keyboard or whatever situation) with your solution? So is it 100 % foolproof or “only” 99 or 99,9 %? Any timing issues with your approach or can a universal timing setup work for 30 wpm up to 150 wpm? That would really be great and make it easier to integrate in the firmware and Agent.
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Is avoiding same-hand triggers not enough? Likely not, when you have additional means to tame the HRM. Which problems persist after not allowing same-hand triggers?