Welcome back Dark Marine
This article in the help section Should help you.
If your map is named ex_city_conflict EX will try and load translations from SourceMods/ex/maps/ex_city_conflict_english.txt when your map is loaded. If you have a different language selected in steam, say German for example it
should try and load ex_city_conflict_german.txt ( I haven't personally tested this, most people seem to be happy with english ). If like me, you version number your maps (eg ex_city_conflict_3) and you don't want to keep renaming or copying your translation file you can specify a separate name using the ex_gameplay entity (eg ex_city_conflict , this way all versions of the map will load ex_city_conflict_english.txt irrespective of the bsp name).
To be on the safe side check that your map name and translation file name are spelled exactly the same and in the exact same case.
If does sound like your are doing it right though. Does anything get displayed when you activate your mission?