Same wish here, been throwing RHBH, RHFH, and LHBH for some time. Sadly the only way to know which hand was used to throw BH is to rely on my memory.
Some sort of boolean flag on the throw should be enough to track the throwing hand and display it in the “throw detail view”.
Then there could be various things that could be built on top of that:
Filter throws by hand
Turn on/off “ambidextrous mode”, which could also determine whether to show/hide UI items
Set primary hand (preselect throwing hand)
Show stats in profile view per hand
Show stats in the Disc view
If necessary I’d be willing to beta test/help make this thing come true.