Finally, I figuered it out how to re-region CitC saves. I had legit got all trophies except the ribbons one, and had a hard time figuring it out, and not much in the comments helped.
Here is how it goes:
Blue Ribbons save, resign it to your profile (Auto Save only, no need for Profile), the go into advanced mode, and select 'A6M939R110015B000.sav' in current file and export it. You will know it is the correct one by the "DLCA_MASTER_P" text on the right.
Now back to your save, go into advanced mode, then select the file that also have "DLCA_MASTER_P", in my case it was the second one, and then import the file you exported from this save set (A6M939R110015B000.sav) and hit Apply.
That's it. When you start the game and start Clash in the Clouds, it should load the save from this set.
https://i.imgur.com/jnyDGit.png
EDIT: correction, for the Blue Ribbons save, you need also the 'Profile' save. But if you are going for the 'Starter Save' then only the AutoSave is sufficient.