I actually liked that Navani bonded sibling. I mean it was due to their desperation both of theirs, they needed to bond in order to survive. But still, sibling could have done a lot worse.
Sibling’s central focus has been to create fabrials to make things easy for radiants. It is clear that whatever fabrials are there in the tower, it had taken sibling centuries to figure them out. And quite frankly, we simply do not have the time for that kind of pace. With both of their understanding of the fabrials, I think together they can make wonders.
Rosharan technology will grow in leaps and bounds which will not happen with Dabbid or Rlain.
so for that alone, I can let go of any other reservations I might have.
As to the OP’s objections, I quite disagree:
Hmm let me see.... Sons of Honor are finished, ilalai sadeas is dead. Almost all of the high princes have been brought in line or replaced. Shallan has left Ghostbusters and we know they want BaM and who their leader Thaidakar is. We know who Restares is. We have honorspren join the radiants and possibly inkspren too. We have willshapers joining and bonding the listeners too. We have over a thousand listeners now and many of them will be radiants and also they will be their own separate country. Venli swore another oath. Kaladin swore his 4th oath and so did Shallan. She also reintegrated Veil into herself.
We have a bondsmith unbound and he is doing some really creepy stuff. We have another bondsmith and tower is alive again and we have learnt so much more about magic system. We have even created an anti investiture weapon which will have profound impact on the future of cosmere. 3 fused have been permanently killed. Rayse is dead and replaced by Taravangian. Kaladin has started a whole mental health movement in Roshar. We have set the terms for the champions duel. Rlain has bonded a spren. Emul has been freed. I think that is quite a lot for one book.