You are right.
In the PFL letter, IRCC states "Only information or evidence pertaining to the circumstances of your entry to Canada, as it relates to the applicability of subsection 101(1)(b.1) of the IRPA, will be considered."
It means they will primarily assess whether the entry details in the PFL such as your first entry date and location are accurate, and are unlikely to consider arguments outside this scope.
If you believe that the one-year bar on eligibility and the retroactive termination of your claim violate section 7 of the Canadian Charter, you may seek judicial review in the Federal Court. However, these cases are complex, and success typically requires a highly skilled lawyer, which can be very costly.