Welcome, Grant.
Specials normally go to a "Season 0" or as "Episode 0" in the season to which they relate (which could be moved to "Season 0" if you prefer that). Is that not sufficient? It's not as simple as just allowing the season name to be changed because the "#" in "Season #" is the index number—and probably should be retained even if a caption could be added (i.e., "Season 0 - Specials").
I don't know if there are any plans for it, but related to this is the suggestion to include an information panel for seasons. In my mind, this would be a special movie-like record (i.e., all the same fields) initially populated with a summarization of the existing episode records (there would have to be a "summarize season" command). The fields could then be edited as required to, for example, add an appropriate poster or banner and a description. If that existed, it would then be very clear what "Season 0" is when selected.
As for list colours, I said recently...
I don't think there could be different list background colours for quality [or favourites or whatever] while still doing the same for seen, not seen, wished, loaned, etc. (each of which can be selected or not selected).
If you don't need
Wish flag as a wish flag, then that should work for you. Using a custom language file, you can change all occurrences of "wish" to "favourite." But for those who wanted both, there would be too many colours required to distinguish all the possible combinations.
But here's an idea that would be easy to implement and use: Allow a different colour to be set for items that are "wished" and "owned." That is wished + owned = favourite. The wish flag could do double-duty, indicating a non-existing movie is wished for and an existing movie is a favourite.