JahLaza
I would look into the effect of Nitrate on the taste of coffee. I know it’s something limited in SCA spec and seem to remember reading it can have adverse effects on taste but not too sure.
The water is just out of spec for not scaling at brew boiler temps and will, of course, scale at service boiler temps. I believe the Elizabeth service boiler runs at a very high temp, so you do need to be careful. It’s a shame because you could live with the latter by just descaling the service boiler (may not be possible with the Elizabeth?). It is always a trade off between water considered corrosive, and water that will scale. The Elizabeth is a special case as the brew and service boilers aren’t isolated - I’m not sure how you would go about descaling one and not the other, or if the brew boiler can be flushed out more easily.