"wondering if I change the voltage regulator will this fix the issue? "
I am not a mechanic so i don't know what some parts are officially called or referred to but im fairly handy at fixing cars from trial and error and I'm keen to learn so i apologise if my question seems silly!
. First question, is the voltage regulator the small box at the back of the alternator held in place with two screws, is about the size of a matchbox and has the two retractable prongs that slide into the alternator?
I had the same issue with batteries boiling in my 01 vx executive 6cyl. Not long after i went thru 2 batteries and then the small box i described above off the back of the alternator was replaced, within doing about 100kms of round town driving the starter motor blew and had visible signs it may be the culprit of an electrical fault i believe was responsible for boiling the battery based on how cooked it looked! !
Perhaps keep an eye on the starter motor if you haven't already solved the boiled battery mystery