What you are dealing with is a structure that looks something like this:

my %_abc=( 
   info => { env=> 
               {Generic =>
                  {
                     "Cat A" => "Value A",
                     "Cat B" => "Value B"
                   }
               }
            }
);
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Your code attempts to create or replace "Value A", and "Value B".

Your ideas are correct .. One individual KEY has a single VALUE.

However, that value can be a REFERENCE, which can contain an entire structure.