After looking at this match up spread, there are a lot of match ups that I disagree with. For starters...
I don't know how your ratios for slight disadvantage, hard, and very hard are since a lot people have different meanings. I'm "just going to assume" that slight disadvantage is 45:55, hard is 40:60, and very hard is 35:65 or worse and if that's the case then well...
Very Hard: If this was pre-patch 1.1.5, then I would agree with Shiek. Now that Shiek has been hit with nerf hammer hard, Mega Man no longer has any really bad match ups. Both Mario and Rosalina either barely beat us or has an advantage over us.
Hard: We beat Villager and R.O.B. Only Shiek is without question hard. I also think Fox is up there for sure, but a lot of us have different opinions on the Fox match up compared to Shiek. You could put Mario and Pikachu there, but it's really a toss up and I find Shiek and Fox to be more difficult than Mario and Pikachu. Even though Mewtwo has the edge over us, I think it's only a slight advantage.
Slight Disadvantage: We beat both Cloud and Wii Fit trainer.
Even: Captain Falcon has a slight edge over us and we shut Ryu down. Also, Mega Man has a lot of even match ups mainly due to his polarizing stats and moveset.
Slight Advantage: Jigglypuff has a really hard time dealing with us and King Dedede is one of two characters that we flat out destroy. Due to tough guy status, Bowser could care less about lemons and live for a long time. I consider that match up to be even. Bowser is really scary especially with rage.
Easy: Ganondorf is the other character that I think we beat pretty badly. Palutena has a lot of options against us for us to have an advantage over her and it's another match up I find to be even. Little Mac is a huge pain to deal with. He may be easy to gimp, but he isn't THAT easy and he is a monster whenever he is on stage (especially Final Destination). I think Little Mac actually might have a slight advantage over us. Then again, online lag could be a reason why I think this.
Too Little Experience: Can't comment much on this other than most of these match ups are either even or slight advantage for us.
This isn't my entire match up disagreements, but rather the ones that stick out to me. There's a dozen or so that I can't say for sure what the mu ratios are as there are so many different characters to learn and analyze. Yeah, 58 characters is a lot I must say.