Tried various guenzel beers but not a schwarz from memory so can't contextualise the reference.
I just think the approach to water chemistry of trying to replicate 'famous brewing centre' water profiles is not the best one. Brew the beer you want to make and acidify appropriately and add appropriate salts.
Maybe dublin water was full of carbonates in 1886. Maybe 3 years later it was different. It's certainly different today. Dortmunder export is a great one - check the supposed profile ( hard sulfatey almost burton like) with the descriptions people like Michael Jackson offer.
Want a hoppy, pale beer? Add salts that will aid that. No need to make the water so full of epsom salts it could cure a constipated cow just because a report says that's what it was like in 1834. Add salts to taste and desired effect as appropriate.
What did Mike do with his schwarz?