I agree with your view for how they’re seen in universe, but “anti-hero” is a Doylian status rather than Watsonian.

Holden follows heroic, regarded as heroic by our 21st century Anglo-European society morality. Alex, while the heart of the gang is more of an anti-hero due to his commitment phobia and run of failed relationships.

They’re all (except Amos (except he kinda is in his own way)) admirable characters, and worthy of emulation.

Clarissa, like Fred Johnson, and to a lesser extent Avasarala (although more so in the books) started off in antagonist roles, and thus tend to be more anti-hero /accepting of less moral choices because of that. Good arcs and development with all of them. But Johnson is more supporting cast, so doesn’t quite get to anti-hero for me on that count, but made difficult choices to make up for past crimes.