That link includes this:  "Until states provide conclusive or actionable guidance on how or if a non-attorney may provide CTA services without violating UPL statutes, UPL will remain an important consideration."

I hope no one is expecting states to issue a news release that would count as "conclusive or actionable guidance."  Most UPL rules come from the state supreme courts, through the (quasi-public) state bar associations.  Their job is to decide cases, not give advice to members of other professions. 

I don't know what state Boards of Accountancy do.  They may have issued rules on what CPA's can do, but do any of them rely on a definition of practicing law?  I would think their job is to define practicing accountancy.  And whenever I see CPA's helping clients form LLC's, or file Tax Court petitions, I wonder what rules allow that.  

To be clear, there is nothing in Title 26 about the unauthorized practice of law.  Well, OK, by allowing CPA's and enrolled agents to represent clients at the administrative level, it seems to assume that states would not be concerned about whether that violates UPL rules.  And it does allow Tax Court to make its own rules of practice, which don't require representatives to be lawyers if they can pass a stiff exam instead.