The current 'Favorites' implementation is nonsensical to me, because they are not shortcuts (what favorites should be) but they are actually custom filtered lists. These should be createad and appear under the project in the left vertical navigation menu.

The logic in this, is that custom filtered lists should be able to contain a selection of all tasks in the space. An organisation often has data pools which are accessible and shared between multiple projects (such as products, members, meetings)

So make favorites what they should be: shortcuts and allow custom (space wide) views(lists) to be created and appear in the projects list.