Assume, you did not add the above plugins to your tiddlywiki.info, and from the shell, using different commands and JS script, you create a few tiddlers. No browser, no TiddlyWiki opened, everything from Shell/Terminal/Console.
I use this method for creating config and state tiddlers on the fly and after finishing the job, I use build to create my final TiddlyWiki. Everything works great!
The questions
Where are those config tiddlers? Nothing is saved on the disk?
Add 1) They are only in the wiki. So if you refresh the browser tab they are gone. If you save the wiki, your config tiddlers are saved according to the $:/core/save/all configuration
Add 2) As so often – It depends. If you do not want, that any tiddlers are saved back to disk. – Yes – It is a possible method for a developer
It is no advised to start a “user facing” wiki that way. Users may think their data is saved and it may cause data loss.