Thank you for responding, @Rook I have read the FAQ, but it is unclear. First it says "You need to make sure your game progress is being synced over Game Center, Facebook, Twitter or Google+". Then later it states "Game Center does not recognize the app therefore will not prompt you to restore your save".
You mention 'normal app', which I read as: the decrypted app with the deb injected.
So I started afresh, used Sideloadly until done. Did get the message "WARNING: could not get anisette description: 'X-Apple-I-SRL-NO'" but I cannot put something else there.
Since it said done, I moved it to my iPadPro, did the trust under VPN and devices, rightclick on Sideloadly in systemtray an clicked 'run an jit.
The app opened with the 'save progress' not set. After playing 2 levels, I tried to search. Did not find it yet, but it is searchable.
But how to change it so that I can have my own saved game into the game? I have iMazing on the Win11 laptop. If I know which files to use, can I inject or copy them over?
Tnx.