This is an incredibly boring matchup. Neither character is well-equipped to approach the other reliably in neutral, so they end up doing a lot of standing around. However, this is beneficial for Wario, since the Waft is very easy to camp for in this matchup, and Rosalina is relatively easy to land it against (mostly offstage, but a well-timed airdodge or U-Air will lead into it, too), so the longer she doesn't make something happen, the better chance Wario has to get low-percent KOs. Wario's Forward-B can be ditched early to stay safe, and if Rosalina doesn't jump, it hits Luma for a little bit of damage; while it's on the ground like this, Rosalina's Down-B will not affect it, so it's a constant annoyance, and it also continues to make it easier for Wario to charge Waft.
Rosalina being so tall is a significant burden in this matchup. Wario's falling U-Air is safe on block and combos into itself and other options (such as Waft) until ~75% (and that's assuming it's not stale). Wario's shorthop immediate N-Air cannot be shieldgrabbed until after avoiding the second hit, which allows Wario to play the 50/50 of whether he will move forward or backward, and the sourspot's high base knockback will send Luma upward at any percent, preventing Rosalina from doing much if she guesses correctly and gets a grab. Lingering hitboxes in N-Air and rising D-Air are relatively safe to throw out in many close-quarters situations and give Wario solid advantageous situations if they hit; N-Air puts Rosalina in a juggle state and D-Air sends Rosalina away/potentially offstage.
When you're put offstage, you live in fear of the Waft, and Wario has reliable tools to make sure Rosalina doesn't escape unscathed. F-Air ends quickly enough so that if you try to hit Rosalina with the end of the sourspot and she airdodges, you get a free punish with most anything offstage, and sourspot F-Air often combos into other things, like N-Air, another F-Air, and Half Waft. Bike helps Wario keep the pressure if Rosalina tries to recover up and away to avoid the situation altogether. Rosalina's aerials are large and imposing, but because the animations last so long, she generally can't risk their use in significant Wario edgeguarding for fear that he airdodges through her and punishes her hard, and Wario already has one of the most flexible recoveries in the game. This logic also makes dealing with juggles against Wario hard, because Wario's U-Air is significantly disjointed and he outspeeds you in general air movement, but N-Air used in a similar position will often trade with attacks, and the sourspot puts opponents right back up, resetting the situation, allowing Wario to hedge his bets, "eat" double jumps, and things like that.
Customs definitely help Wario more than they do Rosalina in this matchup. Luma Warp isn't a significant threat because Wario has very little to fear in terms of her approaching to begin with, and he can focus on avoiding that spot more easily than most characters. Rose Waft trades raw KO potential for free, significant damage whenever Rosalina is in a disadvantaged position or sticks out a move that doesn't hit Wario (the hitbox is truly, truly, truly outrageous), and it takes significantly less time to charge, so it does a lot to help Wario win the battle of attrition. Regular Bike stops the long-range Star Bit, iirc, (and maybe the same for Fast Bike, which makes high recoveries get punished with ease), and since jumping off the Bike is what Wario should be doing in neutral anyway, Star Bits don't make it much harder for Wario.
Wario outdamages Rosalina in most situations, gets a lot more out of the statemate that Rosalina usually wants to manage, has reliable KO setups at a wide variety of percents, is a nightmare for Rosalina offstage, and has an airdodge that makes Rosalina fear pressing buttons. You have your work cut out for you if you want to convince me that it's any better than a slight disadvantage for Rosalina (which is a more hopeful description than I personally think the matchup is, and it's likely to get worse over time as people maximize the options I mentioned, so...).
I guess with your system, I'm thinking -1.5 for Rosalina without Customs and -2 or worse with Customs. She has a hard time.
