I looked at those charts. I would expect higher GH, calcium and magnesium to result in such high pH. It must be from other sources too, which I can't fathom.
What you could do as this is only a 10g is dilute the tap half and half with pure water. "Pure" can be RO, distilled [both purchased] or rainwater. The latter would be ideal, as the pH will be acidic. Set up the aquarium, plant it, with this mix.
For water changes, you could use a similar mix. I've never gone down this road, so I can't offer much as to the values. But diluting the tap with pure would cut the GH and KH in half, which is not too much for the plants and still ideal for the fish. The pH I can't say.