There are a number of issues with will_paginate, as both the strings we pass to it (i.e. model names, "Selected" etc) need translation with pluralisation, as do the strings it uses internally.

In case it helps the next person, I was looking into the internal strings it uses, which are based on Rails i18n (we use gettext_i18n_rails instead). I was trying to extract them with gettext by adding the i18n keys to a ruby file underneath locale/, which the extractor would then find, e.g.

# TRANSLATORS: ← Previous
N_('will_paginate.previous_label')

And also adding the English to the en/foreman.po file.

It didn't work though with pluralisation in the way I expected and I didn't solve this at the time. The plural support had only just been added to the Rails i18n to gettext_i18n_rails bridge inside the latter project, so note that you need the very latest version I think for it to even work. I was trying to do this:

# TRANSLATORS: 0: "No %{model} found" 
# 1: "Displaying 1 %{model}" 
# 2+: "Displaying all %{count} %{model}" 
Nn_('will_paginate.page_entries_info.single_page', 'will_paginate.page_entries_info.single_page.plural')

And then adding the originals to en/foreman.po again.