Yowzers. Nice cleanup.
Not to burst your balloon but the shifting of the 2-phase breaker doesn’t modify the load balance. Meaning: It was probably fine before other than old breakers and dodgy whatnots.
In your existing (new) setup the top left 2-phase breaker is on A (black wire usually) + B (red wire usually) phases (vertically down the left side). So the next breaker in your old config would have also been A + B. The phases alternate down the vertical. It’s not the case that the left side = A and the right side = B.
That neutral bar arrangement is new to me though I suppose “normal” … pretty tight in there.
Looking closer I see you have a nominal 100A (125?) panel and wires … like me you might want to set some upper-limit wattage notifications in Goals as a kind of pseudo-overcurrent alarm. I have a couple set to around 9kW as detailed here.
On another note and by way of FYI: my panel is actually 2 of 3 phases supplied to the building. What this means is that my supply phases are actually at 120deg to one-another versus the usual 180deg so the effective voltage I have is 208 and not 240V. Sense deals fine with this up to a point but Support is investigating calibration issues I have with the solar CTs (that I am using for individual device monitoring). I suspect, though I’m not sure, that this also creates a challenge for detection … in the same way that if you move around breakers/circuits and switch phases after Sense has detected a device you may well lose that detection because the detection is generally “locked in” to the current phase … meaning: just seeing a power waveform and looking at signals for more realtime info is not showing you all of what Sense is monitoring.