most songs have two initial goals to reach a certain score and unlock the two remixes. after all mixes are unlocked for a song, there is a bonus challenge that varies for each one. some of them are straightforward, (like choosing the Green Mix at every Switch Cue), while others are a bit tricky and require to you search though the three mixes to find the goal. 8 of the 33 songs cannot be selected within the story mode and you will need to go to the Song Library to complete their goals once you have unlocked them. once you complete the goals for 15 of the 33 tracks you will earn an achievement:
here is a complete list of the final goals for each track and the Mixes you should select to complete them:
The Shoal & The Shadows
The Hollow & The Haven
The Nation & The Neighborhood
The Press & The Plant
The Capsule & The Cosmos
The Cliff & Bonus Songs
(select these in the Song Library)
Tips for Scout's Song:
it is definitely not glitched, just very tricky. the path cues are the hard part. you can even get 100% on this song and still fail the goal, if you miss parts of the path or hold cues. the streak only checks that you hit the initial cue. here are the amount of cues you should have upon reaching each composition spell, so you can keep track of where you may have missed something.
1st: 18, 2nd: 61, 3rd: 69, 4th: 71, 5th: 85.
if you only have 59 or 60 when you reach the 2nd one, you probably missed a segment of the path cues. as long as you have 85 after the 5th spell, you only need to worry about the path cues at the end of the song. my suggestions are to start with your arms far out to your sides so you have room to follow the whole path. follow the shape and direction of the path and keep up with the speed. also keep an eye on the segments. they should sparkle and burst. if they just fade out you missed it. if you are quick you can also try to look at your cue counter before and after each path, but don't let it distract you.