Your numbers still don’t make any sense or are a century out of date or something.
The KfW also hands out loans to add insulation to existing buildings, U0.14 roof, 0.2 walls, 0.25 floor, so lowest R22.7 in Rankine land. The other numbers are for window, listed buildings, etc. All of that is minimum what’s actually recommended is well ask your architect and budget. There’s only so much that’s sensible to do when it comes to old construction as at some point hunting for air gaps and heat bridges is more bother than tearing the thing down and building new, and the KfW did set the standards sufficiently low so that currently uninsulated buildings at least get something and you can’t just tack on half a metre of insulation to an existing structure either. Mostly it’s the roof that’s missing insulation, walls tend to be defensible as they are and it probably makes more sense to upgrade the heating system.