Dear FSFE
I figured out, that there is a dead link on your PDFreaders.org page. On the spanish page the SumatraPDF Download link links to http://blog.kowalczyk.info/software/sumatrapdf/download-es.html which gives an Error404 instead it should link to the URL mentioned below. Also the URLs to the main page should be updated to the translated page where available.
The current links to the translations of the main page: http://blog.kowalczyk.info/software/sumatrapdf/free-pdf-reader.html English http://blog.kowalczyk.info/software/sumatrapdf/free-pdf-reader-de.html Deutsch http://blog.kowalczyk.info/software/sumatrapdf/free-pdf-reader-es.html Español http://blog.kowalczyk.info/software/sumatrapdf/free-pdf-reader-pt.html Português http://blog.kowalczyk.info/software/sumatrapdf/free-pdf-reader-ja.html 日本語
The links to the translations of the download page: http://blog.kowalczyk.info/software/sumatrapdf/download-free-pdf-viewer.html English http://blog.kowalczyk.info/software/sumatrapdf/download-free-pdf-viewer-de.h... Deutsch http://blog.kowalczyk.info/software/sumatrapdf/download-free-pdf-viewer-es.h... Español http://blog.kowalczyk.info/software/sumatrapdf/download-free-pdf-viewer-fr.h... Français http://blog.kowalczyk.info/software/sumatrapdf/download-free-pdf-viewer-pt.h... Português http://blog.kowalczyk.info/software/sumatrapdf/download-free-pdf-viewer-ja.h... 日本語
Best regards, Michael