Thanks for the info @neounix, it’s very helpful in order to understand better the “insides” of Discourse from the perspective of “I’m learning Rails so that I can help but by God it’s being a stiff learning curve while trying to fix your own installation” 
I’m focusing on Redis/Sidekiq now to try to understand why some embeds are not working since I think that can be “Bake” related, but I can’t sign under that since I’m still getting there in terms of debug (hopefully).
Regarding my issue here, thanks to @Overgrow I could determine that:
-
In fact, the Backup Process did copy the files on the backup but did not restore them into the Discourse Installation. Based on the status and/or fixes of my other three issues I may need to recover another backup on another installation and test again the backup process, but it may be an issue for everyone, don’t know yet.
-
Because of that, the weird behavior was happening.
-
Ended up opening the backup and injecting the missing files onto the instalaltion. It recovered everything without need for Rebaking.
However, the other issues persist (not being able to rebuild the Data container, which I’m clueless about and two issues that are making me focusing on Sidekiq and events, because they may be solved that way: Some Oneboxes (YouTube, specifically) not working and some notifications about “false” edits happening recursively to some users, even though no edits happened. So I think I the new installation may have some issues on its events, trying to figure it out. 