It would be great to add more variables, for example displayname - this would be useful on RP servers, where the player's displayed nickname is usually changed to RP-name.

See dev.bukkit#216

Display name is accessible via a Player object https://hub.spigotmc.org/javadocs/spigot/org/bukkit/entity/Player.html#getDisplayName() which is not available for OfflinePlayer in the serverlist.

Possible solution: store it somewhere onJoin/ onLeave and write it to disk on server shutdown. But I‘m not so sure if it’s worth it tbh...

Waiting for feedback.

Okay, thanks for explaining how this works. It is a pity that when logging out of a player's server, this cannot be used without creating a database.