If the buildings were to be from the 1920s, they'd probably need to be built of brick rather than concrete, although that might just require changing a texture in Blender. One thing that perhaps could be modified with the smaller supermarkets, though, is making the gaps between them smaller: high street shops are situated on prime land, and every square metre not taken up by sales floor is a square meter wasted.
I must confess, I cannot now recall how to edit the descriptions - if you look through Pak64 and find where the existing descriptions for that pakset are stored, however, all that you'd need to do is add them in the same place for Pak128.Britain-Ex.
As to home improvement - that is not identical to hardware in the older sense, but there might be some merit in having a DIY shop from the 1960s onwards, although with a much lower distributionweight than the supermarkets, which could indeed take imported hardware. I am not sure that it should replace the builders' yard, though: are there not still builders' yards serving professional builders, distinct from DIY shops serving the general public?