Commerce Backoffice: Orders combine fields filter says name but means username

The combined fields filter on the Orders View says to "Search by name, email, or order ID" - but what it really means is to search by username. This is confusing because the View shows the name as the customer's billing name, at least in Commerce Kickstart 2.x, because we show the billing name in the View and the user account page. We either need to link the address field with the billing name into the combined fields filter if possible or else change this to say username.

Context: this was a UX problem turned up in a training where a confused trainee was wondering why it was working for "Sample Customer" - since that's actually the sample customer's user name and billing name - and not her test orders. Confused me, too, because searching for "ryan" worked for me - but that's because it was in my e-mail address. : P