You may notice that in certain missions there's a 'Lyrics Suggestions' feature in the Assistant tab. These suggestions come directly from the artist of the song and are designed to help you publish your contribution with more confidence that you've got the lyrics right!
As they've come from the artist, you can consider the words trustworthy and correct. It is, however, important that you proofread the lyrics very carefully, as they're likely to need formatting and structural corrections. The lyrics given in the suggestions tab will give you a handy head start in making the contribution but will almost never be perfect; they're designed to help with the contributions you make, not replace them, so be sure to use them responsibly!