I can see what you mean with the Spinster City Apt. It definitely has more of a downtown-feel to it, but that along with Fiesta Terrace definitely adds a lot more detail to the Apartments area in Level 1.
As for the Houses... I couldn't have predicted or imagined them looking as good as they do in those screenshots. Can't wait to see where you put Frink's House. I feel as though it would be more at home in Level 3, but having all the main Houses in Evergreen Terrace would make more sense since it is a housing estate.
This really is a dream come true for someone who has played the 3 core Simpsons Games for years. You're taking the best buildings from the other games, and adding them into the best game of all 3.
If you want a reference to Steamed Hams, you could just have flames in the windows of Skinner's House? And if you know how to, you can put one of those buzzers on the front door and have it play lines from the Steamed Hams scene.
Some personal preferences would be:
Skinner: Ah, Superintendent Chalmers, welcome. I hope you're prepared for an unforgettable luncheon!
Skinner: Oh, egads! My roast is ruined!
Chalmers: SEEEEEYMOOUUURRR!!!
Skinner: Superintendent, I hope you're ready for some mouthwatering hamburgers.
Chalmers: Yes, and you call them steamed hams, despite the fact they are obviously grilled.
Skinner: Y- Uh.. you know, the... One thing I should... excuse me for one second.
Chalmers: Ah- Aurora Borealis?! At this time of year, at this time of day, in this part of the country, localized entirely within your kitchen?!
Agnes: Seymour! The house is on fire!
Chalmers: Well, Seymour, you are an odd fellow, but I must say... you steam a good ham.
Agnes: Help! HELP!!!
As for my own issues with modding and map editing, it just takes a lot of time for me to learn anything, I've only recently began to dive deeper into Hammer for Portal 2, but even that isn't going well.
Spoiler
Did I catch a glimpse of another building you've replaced next to the Lovejoy House? The President House? It seems to have the same textures as the one from Road Rage, which is definitely more accurate because of the white panels instead of the white concrete, nice touch.