So much is happening in this chapter. In addition to the diary pen pal (who I now think might me Avalon BTW).
There's some spirits that hates artificial mages, Soleia apparently some powerful Saintess that can cleanse/absorb and dispel magic?
Then we also got Avalon who may also be isekaied and goes around erasing baddies.
Also there's a 3rd super scary (adopted??) brother??