IIUC you're not really asking how to "validate the .pl Files". You're rather asking how to find code that's possibly correct syntactically/semantically but that does something in an awkward or suboptimal way. If really so, then chances are that there may not be easy if (any) ways to do most of the things you want to.

After all

"Nothing but perl can parse Perl."

But some checks of some relevance for your needs may already be taken care of by the strict and warnings pragmas, since you did enforce their use anyway, didn't you?