[Discord Logger] Plugin.RaidableBaseEnded: Unknown difficulty: 512

That's because there is no such difficulty "512":

        public enum RaidableMode
        {
            Disabled = -1,
            Easy = 0,
            Medium = 1,
            Hard = 2,
            Expert = 3,
            Nightmare = 4,
            Random = 9999
        }​

Seems like your RaidableBases plugin is not working correctly.

I can't set any difficulties with the free version?

Fixed in latest version