Okie guy your doing a great job , generally! And some of your over kill/ engineering is over kill , but hey your doing what you think is right and will let you sleep better at night , so it's all good .
That being said , and you did ask for comments , so don't be offended when you read mine. I'll just try to be gental and touch on issues I see that other folks might want to do that I see as improvements to details / ways things where done and also code issues that here in Washington , would be major issues with code officals.
The added pony walls won't do much for what you hoped for , they did fir out the walls to flush with the rafter seat cuts , so IF your going to finish all the way into that area with your drywall / interior wall coverings / paneling you've covered that. If your still going to frame in a knee wall so you don't have that small / low ceiling / corner the knee wall would have / will provide added bearing / spread the load support , in a way .
The porch area is great support for that gable wall , I hope ypu provided for uplift as Ok. is tornado country . So holding that porch down in a wind , althought a tornado strike very close is going to do what it wants , so I'm talking more to a close call / in the area tornado here .
How are the post anchored to the concrete? How are the beams attached to the posts? Etc, etc. Thats the weak point,IMO.
Anothet issue are those window on the low pitched area , around here that would be a big no no , engineering bill , with windows right into the corners there very little shear strenght in the walls / corners , same way with the other corner . 4 feet is generally required of wall panel , yes it can be reduced using a alternate brace wall pnl.
The stairs are no where near code , but maybe thats not a issue for you. Others that need to be with in code should disreguard that idea / way of doing it . Yes a code stair takes a lot of floor space. In a small place thats a hard deal giving up that space , but ......
Sure they'll work for you , and your strong railing idea is good . And your way of building them looks to be stout . So all good , unless you have to pass a code check.
I'd also have tied the ext. wall sheathing in better from the main house to the low pitched roof area . I'd guess a wall framing break exists at that area so if you would have staggered your sheathing at that point it would have tied you together better. Try to spread your sheathing joints out / stagger the joints better.
So no offence , I'm I little reluctlant to post this as it could be taken wrong , so just look at it as a what it was intended constructive review.
All in all a very nice job
Keep up the good work , and if you have questions , a photo and question will MTL result in a answer before you press on. Some times we ask after the fact and we all get into problems with the answer
The steel post is super over kill up to that ridge board , if your doing a pony wall at the loft I'd take it down , the way you have those collar ties thru bolted that ridge will never settle even with 10 feet of snow or a pink elephant ;)placed on that ridge . If your doing a wall all the way up to the ceiling / roof under side , just leave it in the framing , some one will be impressed in the future when they remodel the place
G/L , PEG