Let me break it down into three aspects...

formal rules and conventions

I don't think there is generally any problem using another language especially if it's bilingual.

I'm not aware of any hard rule here, and I'd been extremely surprised if using additional languages was forbidden. I'd be even surprised if anyone said that English was obligatory.

Regarding convention:

IMHO as a courtesy at least an abstract in English should explain the purpose.

technical aspect

Please note that adding extra .pod files in other languages and linking to them is easy°. And I'm sure I've seen distros with module_en.pod plus something like module_de.pod

Legal issues

There might have been a problem where spam, radical or criminal propaganda is embedded and can't be spotted/flagged on metacpan because the language is "exotic".

But in the days of automatic translations this should be covered.

And this would be an issue for the metacpan site and not CPAN in general.

Cheers Rolf
(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery

Updates

°) perlpodspec :

> 

... L<name> values are of two types: either the name of a Pod
 page like L<Foo::Bar> (which might be a real Perl module or program i
+n an 
 @INC / PATH directory, or a .pod file in those places

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In reply to Re: Perl module documentation language conventions by LanX
in thread Perl module documentation language conventions by Polyglot

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