Our previous assumptions regarding C3/C2 are more or less in line with the classification by HiG/CundCo.
The current tile list in the store was coordinated by Maik from the German forum with Andreas from HiG/CundCo.
From this follows:
C3:
Mini: The Peasant Revolts (2020)
Carcassonne Basic Game (2021)
Carcassonne BigBox (2021)
Mini: The Signposts (2021)
Mini: The Gifts (2021)
Mini: The Festival 3.0 (2022)
Mini: Castles in Germany 3.0 (2022)
C2:
Mini: Halflings (2020)
Mini: Cathedrals in Germany (2020)
By the way, the graphic artist of Cathedrals in Germany is Marcel Gröber (was confirmed to me via mail by Andreas from CundCo - interesting that this expansion is counted to C2 anyway)
The jubilee edition is counted separately or here is a translation of the mail answer I received from Andreas@CundCo:
"The jubilee edition is an intermediate extra thing.
2.1 and 3.0 (C2 and C3) always applies only to the standard versions"