A few things you could consider adding to the world generation. This mod already has a lot of potential to add the flavor of futuristic Minecraft civilization (I use it as an apocalypse version for my pack XD) and some simple features could improve it even more

0. A bit more flashed out interior there are so many building tricks that can be done to make furniture or the like in vanilla mincraft that could be used to make the insides look less repetitive. As well as placing the spawners and chests in more funny looking places like on top of a bookshelf raw or having a chest next to a bed like a bedside drawer etc

1. Sewers the bigger the city the more likely it should have a sewer somewhere underground. (potential for loot and small dungeons or an add-on mod that makes sewer monsters XD)

2. Airports Rare generation low chance to generate instead of a city

3. Over ground Train station should be a little improved. (benches or an actual station building etc not just a flat clean poke out of the underground part that dives back down again) actually there could be some over ground trains/rails etc as well

4. Gas stations on long roads or general on some roads. As well as some Food Stores like a “Minecraft Donald” or a “Burger Cow” (Or a standard one normal Shopping mall)

5. Playgrounds like with slides and swings XD (addition to parks a chance a park can be X)

6. More building variants currently there are to little and to many of the same type maybe there could be some that gat smaller the way up but instead higher or simply have some features to them like the empire state building or the Chrysler Building the Burj Khalifa or a round one like the 30 St Mary Axe that have a rare chance of being generated instead of a normal building

7. Small improvements for cities if they are set to lower rarity to make them less of an isolated thing inside normal terrain.... more below.

In the case of my modpack “Dimension Zero” for example where I use the lostcitys_bop type chisel profile that i configured as default with a reduced number of cities down from 0.02 to 0.003(basically using the number from rare cities so players still can find a spot to free build and for the bop generation to actually happen if they don’t like the cities) there could be a few things that can generate instead of the standard cites like non high riser parts like more rural areas with small family buildings but still in the style of the main mod just to make the cities less of a random poke out of the vanilla terrain etc. As well as having more of a blend in on the edge of cities to where the standard terrain starts again it looks a tiny bit strange if they are like caged city spots like they where plunked down there in the middle of nowhere.
Here is a small example on how they are spread out atm.

GZ
SirAron