Their GitHub has 0,3% Swift code. They said they start once Swift 6 is out. It has been out for months. So either they abandoned Swift or haven’t really started or they are really really slow to start using it. All three options are against the article being outdated, wouldn’t you agree?
Current blockers to swift usage are found here: https://github.com/LadybirdBrowser/ladybird/issues/933
Rising tide lifts all boats, by trying to use Swift seriously, they're finding and helping fix bugs in the compiler
Because the article is from 2022 and says that they will use a custom language called Jakt which didn't pan out, it seems. Yes, I am also eager for the Swift rewrite to get off the ground.
Just inspiration.