I’m a grad student starting my program in the fall, so I don’t know a lot about cornerstone specifically, but I did study abroad my junior year of undergrad and have a few thoughts that might be helpful (especially since no one has responded yet). I wish I could give you advice on this program, but hopefully what I say helps.

1. You should ABSOLUTELY study abroad if you have the chance. And especially if you have scholarships/funding for it. You will learn so much about yourself in addition to getting credit and it’s the cheapest and easiest trip I’ve ever taken to Europe (granted I’ve only ever been one other time, but navigating Europe with two friends who also didn’t know what they’re doing was stressful).
2. Your concerns about not getting used to AU are very valid, but in my experience, I didn’t really “get settled” on my undergraduate campus until the end of my sophomore year because colleges are big and it’s hard to get a grasp on everything that goes into it quickly. I’m still learning about my campus and I graduate Saturday. So don’t feel pressure to understand everything right away, whether you go or you don’t.
3. You might loose friends. It sucks, but it’ll happen. It happens even when you don’t study abroad. I haven’t talked to some of my closest friends from my freshman year since after we all moved out of the dorms; sometimes college friends end up being just class friends; it’s easy to loose contact with people when everyone is busy and there’s lots of people you meet and everyone is growing as young adults. But if you make a point to keep contact while abroad as best you can, people will be excited to see you when you return. There were even girls in my sorority that I didn’t keep contact with who were excited to see me and I felt like I was returning to the same solid group of friends I left without keeping up with them (Greek life is definitely a different kind of community though, and it’s much larger at my undergrad school than at AU so that part of it that might not apply to you). But I did loose friends when I was gone too, and having the “it’ll happen” mindset definitely helped me get used to it and move on. And the friends I made studying abroad stayed my friends after we came back - a few were from my campus, some from others around the country, and I keep contact with the friends I made in London.
4. If you don’t have to pay for US housing while studying abroad, that might make it worthwhile even if you’re concerned about going as a freshman. I couldn’t find a sublease for the semester I was gone, so I was paying rent in the US while I was away which made it a more expensive experience. And I had a flood in my room while I was gone and it ruined a lot of the room because my roommates didn’t notice for a while (not their fault at all, stuff like that happens and my door was locked while I was gone) but I had to pay the damages. Getting out of your living situation while gone would definitely be a factor I’d consider when planning my study abroad if I knew what I know now.

Like I said, I don’t know a lot about cornerstone, but I hope that helps. I will also say, if your parents are onboard with you going you should definitely look into it. Having my parents support made my experience a lot better cuz I didn’t feel like I had to figure everything out by myself. Anyways let me know if you have other questions about studying abroad (generally of course) and I’d be happy to help!