All I mean is that their reaction in that scene is tinged by the severity of what is happening and the trouble they think he is in and isn't alone a reaction to hearing he has proposed to Selina. I don't think we will get full "reactions" to the engagement news from them individually as by the time we see them next they will have adjusted to the news and the immediate danger is over. Instead we will see their... opinion?
I think we saw Damian's opinion already, now that Dick has explained to him why Batman might do this. He wants his father to be happy, and if this is part of it he will accept it. Dick knowing ultimately why Batman would see that potential in a future with Selina I think suggests that he accepts it too, and appreciates how hard a step it was for him (Bruce). Dick didn't join in on the argument the boys were having in the library because, in my opinion, he had the context of more positive driving forces that might be at play than they did. I think that was why he was so calm waiting for Bruce and Selina outside the entrance, because the proposal was a sign of striving towards something positive and he trusted whatever the reason Bruce had to risk this trip was not one of self destruction.
For the others we will have to wait and see. I can't really see either Jason or Tim having an issue with it as they both have had positive interactions with Selina/Catwoman. I can see Jason relishing it in fact as it mars Batman's patina of "Justice" a bit. I guess it is possible he would feel bitter about the hypocrisy, but I don't think King is writing characters that way, I feel like he would take the path that evens the playing field between them instead. Reminders of Tim playing with a baby Helena make it hard to think Tim would be unhappy, but I don't know him well enough.
For the girls: I'm going to have to think about it.
Edit: I guess I didn't really answer your question. How I think they feel vs. whether it will play out like that (or whether we'll get to see it confirmed) are different things. I think Damian will accept it because his father decided it, but neither happy nor sad. I think Dick would be happy for it, but more importantly because it may be a sign of Batman opening up to possibility of a different future (and if he feels Batman has a shot at happiness with Catwoman that would mean he agrees with it?). The others... I think Clark might be a bit of a romantic at heart and so at heart might like the idea of it but uncertain how good a decision it is (but hopeful!). Maybe Lois thinks it would be good and humanizing for him (and might be amused by thinking Batman doesn't really know what he's getting himself in to) - she seems curious about it for sure. Wonder Woman - I have no clue! Steph - In Batman Eternal Selina opens her eyes to some truths about herself which ultimately lets Steph break free from her father. She geeks out about her too, so unless something bad happened after that, she seems to like her well enough. Maybe the news would be exciting? Cass - I don't know their interactions very well.