This is part of #378 as it is now a feature included in D8 core (d.org issue):
This was something that tested really well on the D8 UX study, and we should consider adding to Backdrop as well.
User interface changes
- Form validation error messages are displayed below the respective form fields that have triggered them.
- A brief indication of the number of errors, and a link to each error is displayed in the messages area at the top of the page.
Drupal 7 inline messages module
Drupal 6 (and 7) ife module
Inline Form Errors unofficial and very experimental Backdrop contrib module by @daggerhart:
~~ Advocate for this issue: @klonos ~~