Information regarding per-region fog Spigot as of now lacks support for the new custom worlds feature entirely. There is a thread detailing this:
https://www.spigotmc.org/threads/sky-fog-color-packet.456700/. Until Spigot adds the API required for this, or that thread is solved, I cannot add support for fog.
Schematic regeneration Support for regeneration via schematics has been added (/rpgregions setschematic). Warnings and confirmations have also been added to regeneration-related commands due to how dangerous they can be.
Please note that MiniMessage support is still work in progress and some messages may not support it yet. Please let us know if you find a translation key that does not support MiniMessage.