The egg layers are the 3 that sleep in the coop, the run roosters don’t even go in coop. The RI Red, first to give me an egg the buff I saw in box, I’m assuming the other buff too.
You say you are assuming. That can lead you down the wrong path. If you want to find out which are laying, look at their vent. A soft big pink vent means they are laying eggs or are real close to laying eggs. A tight dry vent means they are not laying. Once you see it you can easily tell the difference. That doesn't tell you how often they are laying, just that they are laying. You may have more than you think or it may be different ones. Just because they are in a nest doesn't mean they are laying.
Part of the egg laying process is deciding where to lay an egg. My pullets tend to lay where others are already laying. That doesn't mean that all of them do, just that most of them do. Occasionally one will make a nest somewhere else. Each one is an individual and might do their own thing, that can make some of this frustrating.
Do you have fake eggs in all three nests to show them where they might want to lay? I use golf balls, you can get ceramic or wooden eggs at a craft shop. That doesn't guarantee that they will actually lay in the nests but it improves your odds.
I hate to open this bag of worms because some people are likely to freak out because your chickens are sleeping in the run with winter coming. People in colder climates than yours have had chickens sleeping in trees. I don't know how sheltered your run is, these trees tend to be in a pretty sheltered area. In colder climates chickens need good ventilation and protection from a cold wind. You can't get better ventilation than sleeping in a tree or probably sleeping in your run. The question may be if a cold wind can hit them out there. They will probably come down off the roosts if a cold wind hits them and seek shelter but probably doesn't always mean always.
You can train them to sleep in the coop if you wish. Go out there after they are on the rafters and asleep so they are easy to catch and lock them in the coop overnight. When I do that I just toss them on the coop floor and let them work things out about where they sleep. They always do. Sometimes I only do this once and they put themselves to sleep in the coop the next night. Sometimes I have to do this on several consecutive nights before they all get the message. I would not leave them locked in the coop only until they lay, that could be months, but this way you will know that they know where the nests are.
When I’m not around they stay in run.
This implies that they already know where the nests are as it sounds like they go in the coop when you are around. I don't think you have to do anything to get them to lay in the nests when they do start laying.
Do they get impacted if they do not expel eggs?
All are about 25 weeks old…
They can have egg laying issues, prolapse, egg bound, and internal laying. That's generally due to a defective hen, not because they choose to not lay. The vast majority get it right so don't worry about that. Them being late to start laying helps with this. Their internal egg making factory has had more time to mature so they are better able to handle egg laying.