Alas, that never really works with multi account setups. Its sometimes useful for seeing which magic line one is missing, but the level of incorrect boilerplate out there on github is staggering.
I probably could have figured it out, but why bother when we are paying for the business support plan?
I agree that It can be confusing as f for a newcomer. This is definitely an opportunity for training courses/labs/moocs to figure out how to make the learning curve less steep.
also, compared to terraform, cloudformation is state-of-the-art when it comes to actually bringing shit up