Difficult to make total sense of the water, but might it be desalinated? As said, it has very low mineral content, but the exact breakdown is impossible to say with the given information. At a guess I'd plump for 2 ppm calcium, <1 ppm magnesium, 4 ppm sodium, 3 ppm sulfate, 6 ppm chloride with alkalinity somewhere around 3 ppm as CaCO3. If it is desalinated I would assume less calcium and more magnesium than in those figures, but whatever they might be, if they were all zero, any beer so produced would be identical.
Adding acid would reduce the pH of the mash and runnings from sparging and reduce the haze making and astringent tasting products. You don't say what beer style you were producing, but if it was a lager, then it would benefit from six or more months lagering to allow the haze to clear and the beer flavours to improve.
You mentioned ale as the latest brew, which would benefit from calcium salt additions. They would, like an acid addition, lower pH to reduce the quantities of unwanted being produced, but further, with such low alkalinity present there would be no need to add acid and the calcium would deposit the unwanted products produced during the mash, some in the mash itself and the remainder in the kettle if a good rolling boil was ,maintained for 60 minutes.
The level of calcium needed can often be a matter of opinion, but modern text book used in universities suggest for ales a minimum level of 100 ppm calcium is required in all liquor to quickly dispatch unwanted product to their rightful place. When that is done, clearing of the beer will be dependent upon the flocculation rate of your chosen yeast. Some Yorkshire yeasts can clear in hours, Burton yeasts take longer before they drop bright, while there are some that are chosen solely for their flavor profile and can take weeks to clear down.
