I find BizHawk works pretty well from an ease of use perspective. jzintv's also a great emulator in terms of accuracy to the original console, but it's more complex to set up and requires command line arguments to launch games.

I absolutely would love a speedrun mode focused around timeskip once a three-star performance is reached, along with bypassing driving/chalkboards/Onion. Not only do I think that'd make for a very competitive leaderboard, it'd make Overcooked! 2 a much more compelling submission for just about any speedrun marathon that it fits into.

Are the only runs on these IL boards from Trip 1, rounds 1-4? If so, that might be better served by a full game-style leaderboard, 1 Trip (4 Rounds). Making it a full game leaderboard might even help it see more action alongside 4 Trips and 8 Trips.

Having a bunch of empty IL boards that haven't seen much action over the course of five years seems needless.

The category names wouldn't be nearly as cool or interesting, but for the sake of brevity, 3 Levels and 9 Levels might be an option. I've seen some of the Intellivision leaderboards have plain category names like that, with the rationale contained in the rules (e.g., "Complete the first nine levels, as this will fill the treasure list" or something like that).