Literally none of the cast and crew knew.
While we don't have anything to confirm this beyond Disney chitter chatter.
Daisy Ridly didn't end up being the amadeus of choreographed swordfighting.
Even if true, the likely reason behind these choices was 'We don't want the cast or crew to blab'. The sort of people that are likely to get interviewed. Also not after giant leaks that had happened before. 'Hiring Mark hammil and spending thousands to de-age him discreetly' not showing up in the books or budget meetings is literally beyond the ability of somebody like Favreau. Especially not in one of the most carefully controlled media companies in the world.
This is the sort of wishful thinking is what gets people to blab lies like 'There is a civil war' or 'The Sequels will get retconned to an alternate dimension'. Its just bla bla bla they are happy for you to believe so you buy their crap and talk about it if you pirate it.