Perhaps just add a “card properties” beneath tags for less used things? I have always thought mixing leech and marked in with tags was strange as it feels like a flag or something controlled by anki and the tags feel more like user-added. I will also add that most users I talk with are still using marked and leech. I frequently get questions about those functions (at least 4-5x/wk)
The biggest complaint I hear from new users is that they can’t find things or that anki isn’t user friendly (I’m talking 100s of complaints). That is why I continue to suggest making things more organized and available from within anki and not just the manual. I do recognize it means more maintenance for you so I’m not specific about where or how they are located, as long as it’s reasonably accessible.