After speaking to GM Rhojin, they recommended me to create this post about my situation. For brief context, the 6th Star Event chapter rewards are only claimable once per account. As a result, other than for the daily experience and some chapter mission rewards you want, the end rewards are only on one server of your choice. However, I play Reboot NA and Aurora, and I wanted to spread some rewards to help my progression as my Aurora progression is significantly ahead. But also a part of the event rewards, there is an event item called a Star Piece. Although I am not entirely sure what it will eventually do, I am implied that all 6 are required to form something, hence with claiming rewards on multiple servers, I have spread my star pieces and won't be able to obtain the item on either server. I would like to suggest providing some way to transfer that item, provide the pieces to any server the missions are completed on, or if the event eventually reads all the star pieces on the account, then these suggestions are redundant and mute.
tldr: Star pieces spread out on different servers without being able to transfer.
If this has also happened to you, feel free to provide better suggestions or ways to remedy this problem other than the obvious, focus your Chapter rewards on a single server from now on.