The current test page is on http://pdfreaders.julipan.org/. Those files are now sent to our translators. As soon as we have the translations we will update http://www.pdfreaders.org.
We have updated the paragraph with GNUpdf to:
If you want to help to develop a free, high-quality, complete and portable set of libraries and programs to manage the PDF file format and associated technologies, please join the GNUpdf development team or one of the development teams of the listed Free Software readers.
Would be possible to change GNUpdf to "GNU PDF"?