I've done all 60 regular levels, and I think I'm a little under half-way through the bonus stages.
I agree Luna's crap. I've got one or two rainbow objectives on most levels for most masters, but on hers I've probably only got one or two from the ten levels combined.
One of the achievements I got yesterday was for number of rainbows, but I can't remember how many it was (possibly 60?) - and it seems you can't check xbox one achievements on xbox.com - just xbox360 achievements. Unless I'm missing something - which is entirely possible.
I plan on finishing the bonus levels then going back for rainbows - most of which should be fairly straightforward for the first 3 or 4 masters.
You don't need to get all three objectives at once, and you don't need to complete the level for some of them. (ie if you need 400k score, clear all pegs, and get a long-shot on a level and you already have the first two then I think you can start the level, do a longshot, then back out and all three will be ticked. Of course for most you'll have to do the full level though, as the missing objectives are often highscore or clear all pegs.)
Lego Marvel reset to dash yesterday. It's the only time it's done it in dozens of hours of play, so not much of a problem - but it's a little worrying that two games have now done it.