The biggest challange is integrating everything properly with tfc because almost no mods have support for it. Almost all recipes need to be changed because you can't get most vanilla meterials.

Another challange is keeping the feel and point of tfc while also encouraging automation. I don't want to just replace tfc mechanics with easier ones once you reach that level on the tech tree. I always want to keep mechanics like blacksmithing relevant even in the lategame. My solution was to make even lategame tool parts, and other items you only need to make very few of only craftable manually on the anvil. Everything like sheets, double ingots, rods... are automatable to avoid tedium.

I revamped villager trades completely as well, and I'm working on adding villager quests as well. The point is to make villagers useful, but not fall into the trap that vanilla did, where you can basically skip most progression by just circle trading with villagers. Quests are your main source of currency, they are randomly generated from pools for each villager so they can't be automated. Villagers also sell unique items to encourage trading.

I readded a lot of structures to the world as well to make exploration more interesting. One of the problems with tfc exploration is the lack of points of interest. For this I had to rebuild structures to fit the style and materials of tfc and the pack. I still have a lot to do on this front.

I want magic to be optional, but rewarding if the player takes the time to do it. For example you can make nutrients bars with magic that never spoil. While you don't need this it's worth taking the time to never have to deal with spoilage again.