There’s no way an all-core -30 on the curve optimizer is stable unless you have a golden sample. Undervolting is hard to test, since it’s the power spikes from idle that causes crashes. You might be fine gaming since there’s always a load above idle, but you’ll probably get the random WHEA restarts when opening programs at light loads.
I would suggest using CoreCycler to find the unstable cores to save yourself some headaches. There’s always a few cores that need more voltage to be stable - those are the ones you want to identify.