Hello @peterdew, thank you for the update and clarification regarding the language issues you are seeing.
Using the information from the link that I sent previously about using Revit in other languages, you should be able to specify English - United States or English - United Kingdom for the language. More information on this topic is in this help topic (linked from the one above): About Languages for Revit
However, this will affect the Revit interface, and not the families: What changes when Revit uses ENG language versus ENU?
The family library downloads are self extracting zip files containing RFA files in various directories.
If these are not extracting successfully (as indicated in previous screenshots), then this would a problem with the download or your system (not Revit).
Since reinstalling Revit, have you tried downloading/extracting the additional content?
Note: To avoid overwriting existing content (which is working), I would suggest changing the default directory the files extract to (this is an option when you open the library EXE).
Lance Coffey
Technical Support Specialist