Multilingual Markers

At the markers you can pleace a link. I would like to ad different Links depending which language are used by the visitor.

I though about that. But it's not easy to create flexible translation interface.
The easiest way - create different maps for different languages (you can fix language for map). And create clones for placemarks with different translation.
It is not right way, but you can do different translations.
Of use "programming way". Create popup content as iframe, and pass to it language. And in your php file analyze it and create dynamic content based on language.