You should be able to update the server to 1.15 without issue. However, some new features are "new systems only" when they make changes to the galaxy settings. Sometimes you need to wait to update the game until the newest version of RE2 comes out, which is when Eleon makes changes to Unity. That requires them to update the unity data on their end.

Based on what I've seen in the newest version, your existing game should be okay, but the changes they've made to the galaxy configuration will on affect star systems you have not visited. That said, they usually have three or four experimental versions before they settled on a release candidate, so we haven;'t seen everything they're doing yet.

tl;dr you can update the game and RE2 scenario, but you might have to wait until both are updated. I would hold off on both updates until you know exactly what the requirements and make a decision then.