I was looking over the Carl’s sims guide and didn’t notice anything giving benefits for the mixology career. I think that’s odd...I remember reading the gurus accounted for all careers...surely there’...
To the OP: I can confirm that earning a mixology certificate helps with the career. But don't choose the Culinary career, look for a specific career called 'Mixology.' My sim got a nice bonus and started at level 6. I've decided to let her be a mixologist at night and a vet during the day.