Many many restorations (in general) have been approved by someone from the movie team, yet bear a color signature much more consistent with the laboratory's habit than the DoP, director or whatever.
This has been especially the case with Ritrovata (yellow), Eclair (cold blue) and Digimages (yellow) when they're given not only the scan and restoration to perform but also the grading. There are also that crazy person at Fox who turned their color movies all blue (Wild River, Desk Set, etc) and Paramount have a certain recognizable way to want their movies graded. When you can tell where the movie was restored before anything else, that's telling, and it's sadly the case with many of those movies (probably hundreds now).
I still have no idea about what those reference people are approving exactly and when they are called in during the color grading workflow.
EDIT : I found some restoration cards from the AE set, which are likely to be the restorations used by Criterion (a given for One Sings) :
Jacquot de Nantes : 4K scan/2K restoration, Digimages, 2013, OCN, grading supervised by Varda
Sans toit ni loi : 2K, Eclair, 2014, OCN, grading supervised by Varda & Patrick Blossier
L'une chante l'autre pas : 2K, Eclair, 2014, OCN, grading supervised by Varda & DP Charlie Van Damme
Le bonheur : 2K, Eclair, 2014, OCN, grading supervised by Varda
Cléo de 5 à 7 : 2K, Digimages, 2012, OCN, grading supervised by Varda