Thank you for the update! The talk between Barbatos and Zagan and Alshiera's appearance are my favourites parts of one of my least favourites volumes.
This chapter was also very special in Japan because it was released on the same day as volume of 22 where Chastille finally faces her feelings for Barbatos and they have their first and second kiss. It's full of symbolism (like the eel hidden in that cave deep in the ocean representing Barbatos, while there's a tinier fish closer to the glowing surface representing Chastille + that panel with them holding their cups) and it provides a better explanation about why Zagan told those poisoned words to Bifrons. I hope those who had a bit of trouble understanding Bifrons' feelings back in chapter 71 can understand them better now. Sorcerers, even those as cruel as Bifrons, are lonely people, and Barbatos has been as lonely as Zagan was before meeting Nephy all this time.
Also, shoutout to Nephy for the time she gave Barbatos advice in volume 3 of AkuPon. In the light novel, Zagan thought Barbatos was unusually angry when they went to confront Bifrons, but the first one to realize Barbatos' feelings for Chastille was Vepar, then Nephy LOL