PDFViewSkin has lots of fixed english texts:

"Show all / whole page"
"Show previous page"
"Show next page"
"Current page number"
"Total number of pages"
"Rotate page left"
"Rotate page right"
"Zoom"
"Clear search text"
"Search ..."
"Go to previous search result"
"Go to next search result"
"Done"
"Show thumbnails"
"Search text"
"Page "
Bindings.createObjectBinding(() -> "Found " + getSkinnable().getSearchResults().size() + " occurrences on " + pageSearchResults.size() + " pages", getSkinnable().getSearchResults(), pageSearchResults)

as of now, we created our own skin, which uses our own *properties file (de/en/fr). This is very unstable if the original PDFViewSkin changes. It would be nice if the lib would offer some way to change the texts/language.