@ Ellen
RE: Why do you recommend adding a custom text field using Code Snippets and adding a template override, rather than using Advanced Custom Fields?
By adding it the way explained in the dev docs, it automagically adds it as a Content Block Which can be enabled/disabled to display in templates (just like you had enabled the “Custom Fields” content block).
Adding it as a text field also registers is as an option on the Connections : Search settings admin page. Enabling it will tell Connections to also search this when doing keyword searches.
The next update to Connections will actually start hiding, by default, the “Custom Fields” metabox matching core WordPress handling of the same field on its Pages and Posts admin pages. This is not going to be removed, if you find that is does not display, you will be able to click the Screen Options tab in the upper right to turn it back on. Nearly all existing users will not notice any difference, the new hidden default will primarily only affect new installations.
RE: the article you shared states that the template override file will not be re-written in a wordpress update, but are there any cases I should watch out for where it would be re-written?
When WordPress updates a plugin, the existing version plugin files are deleted… So, as long as you do not modify any of the files which exist within the Connections plugin files you do not need to worry about files getting overwritten. This is not a Connections bug or limitation. This is just how WordPress manages updates. Many, many plugin offer ways to use template files which will not be overwritten during updates.
Hope I have thoroughly answered your questions!