My HV battery is at 8 bars and reads 62% charge on Hybrid Assistant phone app

oh ya, you're good to go for the long run. think about it, you've lost 38% in 17 years. that's only 2%/yr.

 

Is the 62% shown in HA a state-of-charge reading, or some kind of life-of-battery estimate?

My guess was it was state-of-charge, and sounded just fine to me. The actual % charge range the car tries to stay in is no lower than 40% and no higher than 80% (with rare exceptions), and the car tries hard to be right around 60% in the middle nearly all of the time (so it has energy to give you if you mash the go pedal, and also has room to store energy if you use the brake).

The bar graph on the dash does not cover a full 0% to 100% charge range, but is more like zoomed in to the 40% to 80% range the car likes to use. A 62% actual state of charge will be shown somewhere in the upper range of the bar graph.

 

I'm pretty sure the Gen 2 MFD only has 8 bars total for displaying Hv battery status.
If SOC is ~40%, only the bottom 2 bars will be on and will be purplish.
If SOC is ~>40 and <~62% up to 6 bars will be lit and will be bluish
If SOC is >~62% through ~80% the 7th and 8th will come on and all bars will be green.

8 bars and 62% SOC sounds off a bit to me. At 62%, it should be either 6 blue bars or barely hitting 7 green.
This is also based on Techstream readings, not HA. Idk the accuracy HA, but you would think it reads directly from the car ecu.