Ok, let's look at the evidence. 1) Grace Randolph is a hack. She's clickbait, and while it's theoretically possible that she has inside sources, it's just as likely that she's made stuff up for clicks. Because that's what she does. 2) Literally no other source out there is reporting this. There are plenty of great places (and a few seedy ones, I'm looking at you MakingStarWars.net) that have legit scoops. Frequently. And not one of them is talking about this, at all.
Can we say, definitively that Randolph is wrong? No, no we can't. Maybe she'll be vindicated in the end. But, at least as of right now, it's foolish to do anything but take what she says with a HUGE grain of salt. Particularly when it's likely that Favreau and his team would have made clear to Pascal what their plan was with the character before they cast him, and he would know full well that his face wasn't going to be front and center in the project.
But, considering how iconic some of the voices (but not faces) of Star Wars are, it's also easy to see him being completely ok with that. Only super fans think about who is wearing the Vader suit. Everybody else thinks of James Earl Jones when they think of Vader. To an overwhelming majority, JEJ IS Vader, even though he was never in the suit. This is no different. A lot of viewers probably don't even realize that Pascal didn't play the character for MOST of the first season, in terms of physically being on set. But the vocal performance is so strong that nobody cares. If this suddenly became a matter of drama during S2 filming, I would be absolutely shocked.