the set-string! docs mention It is recommended you use this function only on UI-related data (e.g. data that is used for display purposes) and write clear top-level transactions for anything else. Calls to this are compressed in history. Does that include form data that is loaded from the server? Or what is the example in which the data is no UI related?

It’s fine for form data…the basic idea is that your transaction elements typically have semantic meaning, and “set string” has very little meaning attached. I should probably just remove the comment…use it as you wish.