Hi, your plot was interesting, so I thought I would give it a review. It has some decent foundations that I think show you have some promise, but there are still a handful of things that I think would really help you take your building to the next level.
I find castle walls in a square shape to be really boring. I get that it is a default, easy structure to work within, but 1) it does not make interesting castles/keeps, and 2) making it take up the whole plot ends up making the plot as a whole uninteresting as well. For 1), it would be much better if there were curves in the walls, and changes in its height as well. Have different towers at the corners, change stuff up. Symmetry is overrated. For 2), if the keep only took up like 1/2 or 2/3 of the plot, you would have room to make some natural areas, or add some outside houses, or anything else to give the build more context. Part of the challenge of building a plot is to make it seem like it isn't a plot. It shouldn't be its own entire separate thing, it should look like a slice from a larger whole. Having the walls go right up to the edges of the plot don't let that happen.
I think you have a good base down as far as the detail of the structures go, but there are a lot of empty areas, especially on the outside of the walls. Adding in the changes from the above point would help make them more interesting, but you should also consider adding more columns/arches along the walls to spice them up, and some texture changes as well to add realism and break up the monotony. There is also a lot of little nooks and crannies between the houses that aren't really being used for anything. Remember that room inside of the walls is very valuable, and every little spot would be used for something. That will also help make the streets feel more life-full.
For starters, you really should finish the rest of the interiors. Now, regarding the ones that are actually finished: There is something I can't quite place, so bear with me as I try to explain this feeling, but the interiors feel very minecraft-y and not very medieval-y. Maybe that is a function of the pallet, I don't really like the cobble and oak wood combo, especially with the wool added in. The ceilings are very plain, which also maybe contributes to it. It just doesn't seem like this was something that was actually built to be lived in, it looks like it is just posturing trying to imitate what it would be like. I'm sorry as I imagine it isn't very helpful to hear things like that because its so vague, so I guess some particular things about the interiors that felt off to me where the large number of torches, the pretend people that are everywhere, and the weird arrangement of the library. I would just suggest looking around at really good medieval interiors (maybe on this server, maybe not) and trying to figure out how to make things be more natural.
I think one of the strengths of this plot is the fullness of the keep area. You did a good job filling the space with the buildings so that it feels like I am actually in a place. And I don't mind the brick, I would say the roofs are also one of the stronger points of this plot, I really like the curves that you put into some of them. I hope this helps you get some ideas of where you could improve on your plot, sorry about the high level feeling based critique of the interiors but I just can't give an exact reason why it feels the way it does.