What version of Rails are you using? I think the Stimulus route is the right path. Vue is acceptable as well, but Stimulus is a lot more light weight.
You can definitely use Stimulus without jQuery. If you are using other JS libraries which require jQuery, you can still pull it into your project, but just write your application's JS without it. If jQuery is being added into your Rails application as a dependency for another library, I think that's fine, but just avoid using jQuery directly as it would then become a dependency of your application as well as the library.
There could be a configuration issue with the Active Storage. https://www.driftingruby.com/episodes/in-depth-look-into-activestorage is a good episode on the setup and usage of ActiveStorage. Also, try to create a new `5.2.2.1` application and minimally add in the Action Text with Active Storage. See if you run into the same issues so you can at least determine where the issue is.
If I understand your question correctly, you may be looking for the `onfocusout` event. https://www.w3schools.com/jsref/event_onfocusout.asp
Within the listener function, you would search for the parent form and submit it through javascript. It looks like you're trying to do an autosave which seems pretty cool and would make for a great episode as there are many approaches to this.
