Tested with Just Dance 2023 TID 0100BEE017FC0000, v65536 (1.0.1), FW 14.1.2, AMS 1.4.0.

Instruction (v2):

1. Update your DBI (455 included) to the latest version, and verify that the console has at least 5 GB of free space.
2. Launch Just Dance 2023, wait for in-game menu, close the game.
3. Run dbi MTP on PC, go to Switch > 7: Saves > Installed Games > Just Dance®.
4. Copy the contents of the 'Cache Data' folder to this folder.
5. Then copy the contents of the 'Offline Gamessave Data' folder into the folder with your %username%.
6. Close dbi MTP, start the game.
7. In game menu, press A, A, 4 times down on the gear icon, A, again A on the icon with a speaker and a musical note, 5 times down on the combined font, A, and select English or your preferred language.
Enjoy!..

..If on the next launch(-es) of the game the save got broken:
— Via dbi MTP, copy the OfflineSaveNx.txt file again into the Switch > 7: Saves > Installed Games > Just Dance® > %here_your_username%.
— On a console, in DBI > Browse Installed Applications > Just Dance > Saves back up your first User Save by pressing + > Backup button.
— For Now in case of an error when starting the game, just do in Restore in DBI on a console, then start the game.

Thanks w350922439, illyasever Gaoda, vinson77 for original savefiles.