I don't have my laptop available to me, so I can't reference the spreadsheet, but I think 5.34 would be fine for a Marzen. In the case of a lighter lager, I would avoid baking soda additions - at least in the mash. I usually can get it into the "zone" by reducing primary additions, which has the effect of reducing the pH drop. But others may have better insight than me and I am willing to be corrected when it comes to water chemistry. I know that some folks further treat the collected wort in the kettle to dial in the pH of the boil.