If your coffee liqueur is on the sweet side, then add six drops of vanilla bitters to help the balance and complexity. However, with a good coffee liqueur...
No no no, use tequilla blanco instead of gin and then taste. I just compared the two and I am in no doubt. The coffee liqueur was Galliano Espresso. Does that cocktail exist? What's the name? Brave Succulent or Brave Cactus?
Well, if you use tequila based coffee liqueur like Patron XO here in this recipe on Difford's, then the freshness of the tequila is allready there to a certain degree. I would say that tequila based coffee liquers aren't the norm, unfortunately. So I stand by my comment :-)