Paying the Piper
The term "technical debt" is a great way for developers to talk about all the work they wish they could have done, or that they should have done in developing the product and getting it ready to launch. At some point the debt piles up too high and you lose a cycle or two just fixing all the stuff that ideally should have been taken care of all along.
Marketing is no different. You cut a corner on some messaging here, you put a campaign live without the training there, you don't tell the sales team about the new feature over there, and pretty soon you find yourself behind the 8-ball. You've got your own debt to pull down.
Just as the product team relies on the customer to validate what they built was right, so too does marketing rely on sales to utilize what they've built. And if you've got stuff to fix, my best advice is to fix it now--do the work to earn back the trust, spend the time to make it right and go the extra mile, and get in alignment with your own key customers on what their expectations are and make sure you deliver.
No one likes paying the piper, but at some point, he does have to be paid. Best to do it now in Q1 then find yourself in hot water at mid-year reviews.