I understand your frustration. In short, I don’t think it’s possible to I’ve been dabbling with FSE themes on and off (I adopted one for a site just a couple weeks ago)
I came to the conclusions/principles that seem to be unspoken or assumed (maybe they’re written elsewhere) about the full site editor:
- Modifications to your theme are meant to be done in the GUI not in the theme’s files (e.g. theme.json, html files). There are some settings that can only be done in theme.json but it seems to me that more and more are to be done in the GUI site editor.
(As you’re probably aware, for users who are comfortable with editing text files ; modify some theme settings is may take longer in the GUI than it would to edit a text file. This also makes version control more burdensome.
As a result, when I made changes to my block-based theme in my local wordpress installation and wanted to apply them on a remote server, I had to export the entire database locally; upload the .sql to my remote server and import the local database dump (granted this can be expedited through plugins or wp-cli).
This was the only way that I found where changes to theme.json and template files would be consistently applied.
In the past with classic themes, I’d just FTP or rsync the theme directory to the remote server.
I had this same question – how to sync changes made to theme files with the block editor , a couple years ago, and it’s still largely unaddressed.