Is there any way to write multilanguage documentation using POD? If no, what should I write it in (I already have POD documentation in English, so I will want to convert it and then translate)?
If you're asking whether POD supports non-English encoding, the answer is a resounding YES. Here's an example of brian d foy's article (in POD format) translated into Russian: http://perlrussia.ru/article/brians-guide/brian%27s_guide.ru.pod
If you are wondering if it's possible to stick multi-language POD into the same file, there's a fairly curious example here: http://cpansearch.perl.org/src/HIO/Unicode-Japanese-0.47/lib/Unicode/Japanese.mlpod
It uses Pod::Multilang
However, i'm not entirely certain how (or even if) it works, as I could not find two examples of html generated straight from that mlpod.
See http://perldoc2.sourceforge.net/ - this is a project for international perldoc