Yes. The whole Etihad nonsense is because the cartel clubs thought we were playing fast and loose with the rules on related parties. So they got the PL to bring in the associated party rules, so these could be applied to deals like Etihad.
On that basis we therefore shouldn't be charged with anything prior to 2021, when the APT rules were introduced. However the other aspect to the allegations about Etihad and other Abu Dhabi-related deals is that they were disguised equity investment as Etihad themselves were only paying a fraction of the actual sponsorship. By CAS demolished this argument, so there's no excuse for the PL charges on that basis either,
The argument about interest-free shareholder loans is more complex. Whether clubs pay the interest or not, it still should have been recorded in the profit and loss account and, if they roll it up, it should be added to the loan and compounded.
Let's use an example of a £200m interest free loan at 10%. The £20m a year is money that shouldn't have been available to spend on transfers or wages, particularly if the club pays it back. If it doesn't and the interest is compounded, that loan increases to over £320m after 5 years, meaning it's attracting notional interest of over £32m.
After thinking about this, what I'd do is add this retrospective interest onto a club's expenses for PSR purposes, as well as any interest accrued since that time, until all the retrospective interest has been accounted for.