Welcome to AA!
Thread moved to FW - General.
When you have high alkalinity, nothing will bring down the pH, short of removing some of the alkalinity itself. A R/O unit will be best for that purpose. As mentioned 50:50 mix of R/O & tap might be just the ticket.
Peat filtering is another method of reducing alkalinity. This is not too efficient. But if you don't have a R/O unit, it may be worth a try. The "recipe" I read said use 1 gal or more of peat in a 5 gal bucket & let the water percolate through the peat. I don't know how many time you have to do this to get the alkalinity down to acceptable levels, but it seems a lot of work to me. <And if you live in a relatively "clean" area, it might be easier to collect rain water to mix with your well water.>
BTW, depending on what kind of water conditioner you have, it might be better to use the water before the softening. An ion exchange unit will exchange 2 of Na (or K) for each one of Mg or Ca. You end up with water that is HIGHER in osmolarity, which is not what you want.