There is a lot of evidence for MBCT for Depression though less specifically for MBCT-L:
Some other interesting studies include:
The Mental Health Continuum from Languishing to Flourishing in Life
The Other Side of Languishing Is Flourishing, Heres How to Get There
There’s a Name for the Blah You’re Feeling: It’s Called Languishing
Coping profiles characterize individual flourishing, languishing, and depression
Mediating role of coping competence on the relationship between mindfulness and flourishing
The following links may be of interest: