Don’t define C-c letter as a key in Lisp programs. Sequences consisting of C-c and a letter (either upper or lower case; ASCII or non- ASCII) are reserved for users; they are the only sequences reserved for users, so do not block them. Changing all the Emacs major modes to respect this convention was a lot of work; abandoning this convention would make that work go to waste, and inconvenience users. Please comply with it.
Sly binds C-c i to sly-import-symbol-at-point by default. There may be other Sly keybindings: C-cletter.
From the Emacs docs (D.2):
Sly binds C-c i to
sly-import-symbol-at-point
by default. There may be other Sly keybindings: C-c letter.