Because of the different scales of the translation and rotation, I find myself matching the start of the animation, then moving to the end of the roll, and finding out that I messed the start or the middle.
After fixing the start curve the end is not accurate again.
I'm doing it over and over, and I'm starting to get scared of changing things (for example I used broken tangents for the wobble so I won't screw up the rolling before that).
Is there a better way to match curves?
Well, a few tips come to mind. Try to hide the curves that you don't need. Make sure that you don't create duplicates with inherit properties. Work with solid numbers: i.e. if you want to move an object (or a key) a few points up, don't do box select, just select that object, press G / Z / Num 3.
And don't rush. Having some troubles is totally fine. Take your time to understand the process, maybe repeat some lessons or rewatch some tuts and try to do something offline, by yourself, not after the teacher. That helps a lot too.
Hey kkoko0, that exercise is extremely difficult but it's all about getting you used to dealing with all the issues you have mentioned as well as training your eye. It's like lifting weights for your skills. It's designed to make you stronger.
One thing you might like is to 'normalize' the graph editor view.
This will scale the view of the curves so they all are the same height. However, this can be deceptive about the real value and slope of the curve. I'm not a fan at all but I know people who are - it's a matter of preference but it sounds like this might be something that you will like.