Language change doesn't propagate to combo boxes

[petebrew]

If a user changes the UI language, although most of the interface changes the items within combo boxes do not.

To reproduce, launch website in English, go to 'Advanced Search' then change the language to Dutch. The static text on the page changes but the combo boxes do not.

[PaulBoon]

It seems that the dropdown lists are not updated after a language change, but the rest of the GUI is.
A reload seems to work; by clicking the 'Uitgebreid zoeken’ (Advanced Search) and then it is updated correctly. But this is a workaround.
Somehow the language change should update the whole page, but this needs to be investigated.