I can’t imagine Emilie getting demoted to recurring status, no matter what amount of screentime she does or doesn’t get. They’d want her exclusively for their show, wouldn’t want her going off to star in anything else, and keeping her on contract as a regular, giving her the pay rate of a regular, is the way to do that. She’s not just some random actress, she was part of LOST, so she’s probably sorta like family to Adam and Eddy in a sense. They didn’t have that sort of previous relationship with Meghan, which may have contributed to how she ended up getting demoted. Good point about Sean probably getting regular status if they do bump someone else up to that level.
I don’t think it’s right for Adam and Eddy to keep Emilie around just in case they need her; in fact, I think it’s wrong. It’s pretty clear that Belle is nothing more than a walking storyline for Gold and while I have zero problems with her being a huge part of his arc, I have many problems with her rarely being seen. If they don’t need Belle except on rare occasions, then Belle should not be a regular. I’d hate to see Emilie lose her steady job, but she’s an actor – she has to want to work. She deserves to be freed up to look for actual work. If that means that she’s unavailable when they need her, so be it – the show would have to make do. It’s not like they think she’s that important – if they thought that, they’d make far better use of her.
As to family, it’s lovely that Adam and Eddy adore Emilie personally, but that doesn’t mean mucdh as seen by her utter lack of air time. They asked her initially if she wanted to play Belle because they thought she’d be perfect for the role. IMO, they should only keep her as a regular if they value what she brings to the character – no other reason.