Regarding Edvin and season 2 of Heated Rivalry, here is the take of a bookstan, someone who has been a fan of the books since they were first released.
When TLG came out and we got a deeper look at the Centaurs (beyond the superficial glimpse seen in Role Model) several players caught fans' attention. However, Luca was the one fans most wanted to see get his own book, largely because Rachel had dropped easter eggs hinting that he might be queer. She actually took the first step toward that; the seventh book was supposed to be about Luca, and she even started writing it. But, as she explained, it would have meant having too many queer characters on the same team, and the fact that Luca was still so young ("a baby") made it difficult for her to properly develop his sexuality. So, she sort of abandoned the idea.
In my opinion, since Unrivaled is another hollanov book, focusing, among other things, on them playing together for the Centaurs, Luca might well get more time in this book (given that Rachel already had some material written about him). This could mean that, in a potential adaptation of the book, Luca would also have a more prominent role in the series. Another important point is that Jacob slightly boosted the importance of certain characters in season 1—Svetlana, for instance. She had a much bigger role than in the book, yet hollanov storyline didn't suffer in terms of screen time or significance—unlike the decision to dedicate an entire episode to Scott and Kip. From what Jacob has hinted at in interviews, we won't be getting standalone episodes for specific couples; the storylines will be developed simultaneously.
All this is to say that I truly believe if Edvin is chosen to play Luca, it won't be a minor role for him. And considering there is at least one more season confirmed, a lot could happen with Luca's story. It would be great for Edvin to be part of a mainstream series again. Also, Edvin is represented by CAA in the US, the same agency as Hudson, Connor, and Jacob. CAA is known for connecting its clients to the same projects, especially successful ones 🤷🏻♀️
I hope you are right! Its so hard for me to give much comment since I've not read the books but it's absolutely possible that they choose to give him more attention of they plan to develop his arc further in the next book. Though I don't mind a smaller role either.
I do kinda think the author is low key bullshitting with her reason for not making a book about him like she planned. I think it's about what is popular and what sells. But this is me making up something from my ass so. Take it for what it is. But yeah I think she wants her books to sell and she has something immensely popular at her hands already