Helping my kids

I recently had a totally amazing family vacation in Barbados, a year into my work with Brooke. It was everything I have learned in action and I could not be prouder or more amazed at myself (or my bikini body!).
I do have a question and wonder if I am getting this right. I have a son 27 and daughter 25, and they are constantly annoying each other and coming to me to complain. The old me would have tried to fix this and asked each of them to change their behaviour — I can see the point each of them makes that the other is annoying.
The new me just accepts that they are not always going to get along but sometimes they do.
So when they come to me in frustration and say my brother does this or my sister does that, I tell them there is nothing they can do about it. That each of them will be who they are and do what they do and they can only let them live their life and enjoy the good moments.
I had a feeling I was being unhelpful or high-minded by basically telling them ‘yup, he’s annoying, get over it.’
They (individually of course) came to me and said they were doing it and kind of just ignoring the bad stuff. Is that it? I am not sure what I want them to do is ignore each other’s faults as much as enjoy them.
At this point after a year of this work, I am worried that I am to smug in my ‘advice’ and not sympathetic enough.
I want my kids to set themselves up for a lifetime relationship and have each other’s backs, to me it’s a relationship that will play out in all their other relationships.
Maybe my question is this: what is helpful and what is coaching people who don’t asked to be coached. If someone comes to you with a complaint, is that asking you for coaching? Does one offer advice?