Updating an advanced template from 3.11 --> 3.12 and wondering if simply adding the new 'guidance_hints' column would suffice for this update?
The key changes to the Advanced template for the 3.12 release include the addition of the guidance_hint column as you mention, as well as a guidance_hint::language (xx) column (to demonstrate that you can provide translations for guidance hints!) and also the body::esri:visible column. Other changes include minor updates to the data validation, and changes to the information on the supplementary worksheets.
If you choose to manually copy and paste a survey to a fresh version of the latest template, please see the Updated XLSForm templates for Survey123 blog post for a few best practices that might be of use when migrating a survey to the new template.
Hope this helps. Best, Jim