Literally read the whole report twice, and this article.

It clearly states on page 6 the definition of "indian country" and lays out what that scope is. Page 9 clearly also states that tribes have jurisdiction over tribal members/citizens. Multiple pages address the application of federal jurisdiction.
The article above also says "Lindemuth's opinion doesn't address banishment directly. But in an interview, she said tribal banishments raise constitutional questions that only a court case can resolve. None of the recent banishments have yet been challenged in court."

Now, since many towns don't meet the definition of "indian country" for jurisdiction and the tribe does not have control over non-members that would mean that banishment of folks is a massive gaping hole. Federal law application would state tribal courts attempting to handle this is a violation of a non-members 4th, 5th and 15th amendment rights governing due process of law.