I use an MG 2.3.4 installation and add the splendidinternet/mage2-locale-de-de component to apply German as used language for the frontend. It works. I also use a simple custom skin, based on Luna.
Now I add a de_DE.csv file in the i18n folder of my skin and change some translation with success:
Shipping, Verpackung und Versand,,
The default translation for Excl. Tax
is not good, and I try to change the translation in the same way without any success. I add these strings:
(Excl. Tax),(Zzgl. MwSt.)
"Excl. Tax","Zzgl. MwSt."
Excluding Tax,Zzgl. MwSt.
deploy and flush cache. No change:
I also did a full-text search an all installed file, and I found only the component above. I have no further ideas :-(