Intercepting all translations in Plone 5.2

I have some add-on where the UI only shows up with the english original strings from templates but not with the configured DE translations. What is the best place in Plone 5.2 for intercepting all translations from templates? I checked the code in zope.i18n, and inside luck.

Related bug report

I assume that this is some incompatibility with the Chameleon render..