As was mentioned by Hugomizz, RO strips everything, KH, GH, TDS, ... Water softeners will remove the GH, leaving the rest of it alone. I wish I knew what makes up your GH. Typically it is calcium when it comes from limestone water sources and with lots of calcium, if the KH is of the carbonate type, again typical of the limestone type water sources, the pH should be about 8.3. The only way that the pH should go above 8.3 is if there is insufficient bicarb, or insufficient calcium, as the bicarb will react with the calcium and form calcium carbonate, ie limestone solids, not affecting the pH. If you are measuring the pH with the drop type test kits, they are not very good at measuring the pH at high or low numbers. Look at Amazon for a pH pen and get some calibration solution at the 7 and 10 pH values to be sure the pen is giving good readings.
Zone 7 A/B
Keep your words sweet. You never know when you may have to eat them.
Richard