I mean in the rulebook it is not labelled an independent commission.
Burnley and Leeds have asked for an independent commission. So they are not the same thing mate.
If the PL refuse to convene such a commission (which given no breaches have occurred would seem logical) they could look to sue. I doubt they would, as frankly theyd have a very weak case.
An arbitrator would have no power. They could make recommendations, and it's up to the PL whether it chose to override what it did previously.
Crucially, all of the above takes lots of time, and may mean some sort of warning in the future. It will not be resolved by tomorrow, or June, or the start of next season.
As you have stated though, it all really relates to the PL, and whether they were right to accept independently audited accounts by accounting professionals. I'd say they were fine in that regard. But if they were deemed wrong to do so, maybe whomever goes down, some years down the line, will have a case to a settlement.
In reality I doubt it. As no rule breaking has occurred.