Searchstax config page does not behave as expected when overridden by settings

drunken monkey → made their first commit to this issue’s fork.

Thanks for reporting this problem and sorry it took me so long to get back to you.

Unfortunately, what you’re describing is not really a problem in this module, as the forms that deal with the server entities are actually provided by the Search API module. However, the problems with config overrides go much beyond that: while we already fixed some of the more serious problems for Search API in #2682369: Fix problems with overridden config entities → , there are pretty complex problems with the whole concept for any kind of config entity. See the Core issues 🐛 Inconsistencies when updating overridden config entities Needs work and 🐛 Prevent saving config entities when configuration overrides are applied Needs work which try to address these problems for Drupal in general. As you can see, they have been opened in 2016/2017 – the problem is just very, very tricky to resolve in a way that does not lead to new problems in edge cases. (I also wrote a blog post about the various problems with config entity overrides back then, in case you’re interested in a more thorough explanation.)

All that is to say that we can’t really fix these problems in this module, your best bet is to follow (and potentially help) those Core issues, especially 🐛 Prevent saving config entities when configuration overrides are applied Needs work (as the other one has been stalling for years).

The difference between the search server settings form and the “Performance” page in your screenshot is that the former handles a config entity, which is a lot more complex than a form for a simple config object as in the latter case. So, for normal config objects, Core already includes a pretty good solution to at least warn users about what’s happening.
Which brings me to the one thing we can actually do in this issue, for which I have just created an MR: fix the “SearchStax settings” page (/admin/config/search/searchstax) to display the same warning as the “Performance” page for any overridden values on that page. (Which is what the issue title actually sounded like to me.)

Merged.
Should now be fixed (i.e., a warning should be displayed on the “SearchStax settings” page, if applicable) in the dev snapshot of the module and the fix will also be included in the upcoming 1.7.2 (or 1.8.0) release.