Generating a pdf from the search tab in GeoNetwork 4.2.x or 4.4.x does not respect the language

[archaeogeek]

Describe the bug
When using GeoNetwork in a language other than english, generating a pdf of a single or multiple records from the search tab only includes english labels. This is not the same as downloading a pdf of a single record from record view, which has the correct labels.

To Reproduce
Steps to reproduce the behavior:

1. Set up a second language in GeoNetwork (or switch to french)
2. Select one or more records from the search page
3. From the selected actions menu generate a pdf
4. Note that the element labels are in english

Expected behavior
The language of the labels in the pdf should respect the language of the gui.

I have looked at https://github.com/geonetwork/core-geonetwork/blob/4.2.x/web/src/main/webapp/xslt/services/pdf/metadata-fop.xsl and as far as I can see, the elements should be translated. However when I print the value of /root/gui/language in that file it returns eng regardless of the language I have set.

Note that I have also tested https://apps.titellus.net/geonetwork/srv/fre/catalog.search#/home and the same issue occurs there.