I find it hard to believe that the connected machines have no tag layout patterns that repeat in various ways. Not only do you not need 1:1 UDT versus machine, but that is actually quite rare. Even if you need manual mapping of OPC Item Paths, UDTs can (and should) enforce repeatable tag names to be used with repeatable UI components/views/templates (via tag path).
If you can get your arms around the repeating patterns you need for efficient UIs, you might find something like my Spreadsheet Import Tool helpful. Or a customized version of it. I strongly encourage you make something your "source of truth", and not try to go in both directions.
FWIW, I rather like Excel as a source of truth, as it is very friendly to non-programmers and non-engineers. I'm happy to manipulate Excel spreadsheets with Libreoffice, avoiding the uncaring/unfeeling Borg that is Microsoft, without fear of obsolescence.