Your proposal concerns the underlying Q&A engine that powers all of the Stack Exchange network, so the best venue for it is the Meta Stack Exchange network-wide meta. However, that doesn't mean that it is off-topic here -- and, indeed, posting it here allows for a useful gauge of support from this site's community. SE is currently restructuring its process for taking up user feedback on metas and it's important to take them up on the opportunity.
As mentioned in the comments, the ability to organize the Favorites list is a long-standing feature request on MSE, and has also been suggested on this meta previously. However, I would treat those threads as valuable historical resources, and instead look to the future: again as mentioned in comments, the dev team is currently implementing the ability to 'follow' questions, and that effort includes
on its mid-term future goals as a just-rolled out development a restructuring of the Favorites section, which will be has been renamed as Bookmarks.
So, now is a perfect time to put a word in for this feature, and hope for support. One good place would be as an answer to the original announcement, but this is now closed as a duplicate of the rollout announcement, and I don't think an answer there would be useful. I suspect the best way to go about this is to post a new feature-request on MSE pointing to all of these precedents, and asking explicitly for this feature to be built into the next dev cycle. There's no need to close this thread -- just edit in a link to the MSE thread here if you do post there.