The following code is what bothered me:

   my %defaults =  $caller_is_obj
     ? %$caller_is_obj 
     : %_default_data;
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Instead of that do the following:

  my %defaults = $caller->get_default();
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and in your module define a get_default() method that returns the same data you put in %_default_data.

Either that or change to:

   my %defaults =  $caller_is_obj
     ? %$caller 
     : %_default_data;
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(which upon reflection is more likely what you meant).