Yeah, no. Approaching Rosa is a BAD idea. Like Lawz said, jumping offstage to challenge one of the best offstage characters is suicide; now if you trap Rosalina off the edge without a jump Link can do a decent job of intercepting her upb which has no hitbox, especially in combination with projectiles, but smart Rosas don't let that happen often. Even then, she edgeguards us way harder than we do her.
You can try to aim arrows above Luma to pop Rosa with, but she can absorb them. Same with boomerangs. You can cook bombs for a few seconds before throwing them, which makes them harder for her to deal with (if she gravity pulls them it lands at her feet and either blows up or only lets her immediately pick it up and toss it if you cook it a little first). Dthrow >utilt does NOT work on her because you will hit Luma first causing hitstun and giving her time to airdodge and punish. Also, if you ever knock Rosa away you need to shield or you will get nailed by Luma flying back to Rosa. Uair strings work very well on Link; bombpulling up in the air is risky because Rosa jumps so high and has a huge uair hitbox that can kill early if you're not careful - be cautious with airdodges that high too because Rosa can read it and delay her uair until she gets the double hit with Luma.
Luma makes this match up much more difficult; Rosa is much easier to deal with when Luma is gone, but it's still hard to press the advantage too much since it's only gone a short amount of time and Link isn't exactly the best at rushing. 35-65 Rosa's favor, MAYBE 40-60 but I think that's kinda generous. Not unwinnable but this is an uphill battle.