I cannot agree... bicycle tag is legal access to a path, not difficulty,  here the table for routing:
https://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access_restrictions#Italy
You should warn the router's author that his software should use that page as a reference for supported countries.
Putting bicycle=yes or any access tag is a repetition of defaults that makes heavier the database and doesn't give anything more.