I think these are new - there's a comment on the project page asking about "playing the classic Red Alert maps" and one of the devs replied they would require some modifications to work.

Besides, original missions can be played with OpenRA so I don't think they would port them here without at least adding support for the new factions (which in turn would require changes in story?).

That's just my guess based on some research though, I'm not a specialist when it comes to these projects.