(FINAL Update )...Alternator voltage too high, question

Voltage regulator is what is says.
Most of us associate it with alternator brushes, as that is the only way in US to buy, but the unit has electronic circuit inside as well.
When the circuit fails - whole thing needs to be replaced (you can save good brushes for re-soldering them next time)
With readouts >15 V there is not much to think about.