I’ve noticed the same issue with unfavouriting forum topics. The steps you’ve outlined perfectly describe the problem I’ve encountered as well. The missing image/icon and the link not removing the topic from favorites are indeed frustrating.
I also share your enthusiasm for BuddyPress and would love to see some enhancements, especially the ability to add a Favorites button to individual blog posts and coordinate it with the Activity feed. It would be fantastic to have a listing of favorite blog posts in the profile, and extending it to comments would be the cherry on top.
Thanks for bringing this up, and kudos to the BuddyPress team for their hard work! Looking forward to seeing these improvements.