@Niklas, that's a great idea about the guards statements, a little more diversity would never go amiss!
@Defender, the goblin museum stuff could definitely be looked into, it currently can change in two ways, if the blackmarket is ruled by a goblin, it will have an extra panel in the tour and new dialogue showing off the goblin ruler, also if a non-goblin blackmarket ruler bans goblins then the goblin hall will be closed down until the ban is revoked, so it's already kind of in the game, would be cool for the player to be able to trigger this themselves though I agree!
The tower of histories could stand to be grown a little more, perhaps with an npc caretaker, but I don't think the two should be merged, the tower of histories is bias to the east as it's an eastern institution whereas the history guild gets some things wrong too, both are separate imperfect institutions in a large world, I think it makes sense for their to be various different kinds of things.
As for the guilds of guildrow, it's a complicated one, speaking strictly about development, the blackmarket was a teeny tiny location where you could do one or two things, like hire bandits, attack or play a coin flip game, it was pretty sorry looking, but I loved the idea of a blackmarket, I really wanted the feeling of a shady place where all sorts of things went on and where different players could have a whole different experience and completely miss whole locations and cool things because of it's size, as it grew and was split into districts I ended up adding guildrow, while I had the same thought process as you at first and thought it might be a bad idea, the lore behind it is that the institutions in guildrow are exempt from taxes to encourage guilds to stay there, it's kind of like a medieval tax haven, the guilds add an air of legitimacy to an otherwise illegitimate den of crooks and ner-do-wels, and for me at least, over numerous playthroughs it has succeeded in making the blackmarket feel more like a dark seedy town with good parts and bad parts.
I agree with your ideas about adding ability to expand it, currently this is sort of already implemented but I have massive plans for the blackmarket in the future, for now if you upgrade the blackmarket you get new areas and all previous areas get improved so it's worth checking out!
@Soulkeeper, thanks, hope you enjoy it
@Niklas, exactly my feeling about the market! glad you feel the same it's my favorite location
let me know if you find those typos, I'll investigate! cheers