The recently played list only shows the 2 most recent servers you played or it removes the most recent for the new one not sure which way it works, you can just go through the server list and pick the server you want if you are playing more than 2 servers. The ninja is still there just you have to manually pick the server now if you keep playing on 3 different servers.

No your level 58 will be on the server it has always been on, just it doesn't show the server in recent as when you changed to another server the one with your 58 on is no longer the most recent server. The ninja is on the same server it always has been you just have to manually go through the server list and select it's server. When you have done this then that server will again be in your recent server list.