The only Perl modules that shouldn't be architecture-independent for the purpose of RPM are ones that use XS. But it's pretty clear from how the question was asked that there's no XS involved here. Your script could depend on modules that use XS, and hence are architecture-specific, but that's no reason to make your script architecture-specific unless you bundle those modules with your script's distribution.

Labelling those dependencies is another problem. It seems like older perl RPMs provided things like "XML::Simple" or maybe it was "perl-XML-Simple". Newer ones now seem to instead provide "perl(XML::Simple)".