Track UI message improvements for Create in 14.6

Problem to solve

As a follow-up to #346051 (closed) we should track the changes to error messages that land in 14.6. I can link this issue to the epic &6436, so we have a chain from the individual MRs back up to the original plan.

Further details

Spreadsheet of all work is available.

Proposal

Who can address the issue

Other links/references