There is no "standard include path" for the "Perl engine" - the include path widely varies between different installations, so your description is of no help.

Looking at the source code of Data::Phrasebook::Generic, you can likely patch it to make the error message more descriptive:

Replace:

croak("no loader available of that name\n") unless($plugin);
[download]

With:

croak("no loader available of the name '$class'") unless($plugin);
[download]

Also, you can set a debugging flag with Data::Phrasebook, and I recommend doing that.