Totally agree on the value of having one standard and sticking to it - in an ideal world at least.
In the reality of this team, though, I’m super scared that we’ll just be doing groundwork forever. Already we see week/months of work on adjustments blocking the tax reports. The reality is that we won’t create officially supported endpoints on these reports unless we can find a way to be agile.
If both of these things are requirements to supporting API endpoints then I suggest that the scope creep is too large and thus tax reports endpoints will not be the first officially supported API endpoints. 
Thanks for the info 