HTML::Template internally represents data as hashes of arrays that have hashes in them. This is an example from the perldoc:

       $template->param(EMPLOYEE_INFO => [
                                           { name => 'Sam', job => 'pr
+ogrammer'
},
                                           { name => 'Steve', job => '
+soda jerk'
 },
                                         ]
                       );
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If you read in your data using XML::Simple it will be represented in almost the exact same structure (depending upon the parameters you set in XML::Simple).

So the answer may be to just use XML::Simple rather than Class::PhraseBook to implement your solution.