Thanks for adding Flat Keys as the Circle of Fifths preference! I work more in Flat Keys than Sharp Keys and find this very helpful. I think all levels of users will derive great benefit from this small but important musical detail. It adds more professional polish to the program. Well done.
it is right, but in harmony studies, in C, Gb is a fifth dim, we are in Db and F# is a fourth aug, we are in G
Cours d'harmonie - 2.8.1 - Enchaînements avec septièmes de dominante - YouTube]