That's some seriously impressive architectural and detailing work!
I think the thing I love most is the way you've used the stone colours, fading ever so slightly as the building gets higher, to blend into the natural stone's gradient. That makes it so much easier to believe the mountain is really that tall, rather than looking like a tacked-on addition. Disney's set and theme park designers use a similar trick to make their buildings look taller, I think it's called "forced perspective" but what I remember for sure is that it uses a slight colour fade + a subtle reduction in scale as the height increases to trick us into perceiving that the top of the building is further away than it actually is. Whether you've done that consciously or instinctively here, it works brilliantly and makes the facade look even more impressive!
It is my personal opinion that no Dwarf hold is complete without some ancestor statues out front to guard over it... but that's just personal opinion. If you're looking for something to fill that courtyard/plaza though, that would be my recommendation.
Whatever you build on the inside, I hope you have enough space left in your town's inventory to build a suitably grand treasure room in the deepest vaults. If you want inspiration for the inside design, you may want to check out @micheal_handy76_mh's Stoneden, which has some very cool and luxurious interior decorating.
Clearly this build has been a labour of love, and it's looking utterly awesome; but in true Dwarven fashion a craftsman is never satisfied until their masterwork is totally perfected... heheh. I'm very excited to see this progress!