No, both of his flashbacks were from after the plot the started. The first being about his deal with Kirschtaria and the second about his perspective on the things Morgan did. There was some extra confirmation that he comes from a witch family but that's kinda old news and still not elaborated upon.
But we did get to see what he can do in terms of replication and curse transfers, and we got a decent look at how his mind works. Stuff like the source of his hedonism and how he chooses who he kills and who he doesn't. Beryl's big thing is that he doesn't value life, be it his own or of others. He views living as a chore he needs to offset with
to make it tolerable. Even so, he still thought he'd never want to kill Morgan or Kirschtaria because they were, as far as he could tell, happy and boring.
All he cares about is killing two categories: interesting people and tragic people. He mentioned Barghest as his example of an interesting person but didn't elaborate on that entails. And his example of tragic person is Lady Spinel, as she's a sheltered princess absolute desperate for Morgan's attention, which she won't really get no matter how hard she tries, so she's wasting her life and would be more comfortable dead. Beryl's mind frames his murders of tragic people as genuine acts of mercy and love.
The way he's been using Lady Spinel is really interesting imo. He made her attack Woodwose with a super powerful curse that rots the user's soul because he knew this would make her feel super useful to Beryl. He went somewhat out of his way to pair up with her in a proper Master-Servant duel against Fujimaru because he knew that's what she wanted the most. He let her cast Garden of Lost Will on Fujimaru and Arthuria even though that would drain her so much that she'd get paralyzed and her fingers would start falling off because he knew this would make her feel really useful to Morgan. It's really looking like his approach to killing tragic people is keeping them on the illusion of achievement until the very end. He's often seen as annoyed with Lady Spinel and there's no reason to doubt this annoyance is completely sincere, but even then his actions substantiate his claims that genuinely loves tragic people, in his own fucked up way.
Now getting into speculation territory about his future plans, he already said a lot about his love for Mash and his description of Spinel emphasized some points she has in common with Mash, such as getting starry-eyed from hearing about "the outside world" and being an instrument to a dry leader who will never love her, so it's no stretch to see say (pre-part 1) Mash was a tragic person he wanted to kill. He also has an one-off line where he refers to Fujimaru as "the main dish". Taking it into the context of his replication works and his MO handling Baobhan Sith, his endgame is probably to kill and replace Fujimaru, and finish part 2 together with Mash in a way that she dies, either during the final boss or during the epilogue, thinking that Human Order will get back to the original version.