It requires l10n_en.xml as well as l10n_en.xml. After that, your problem should be resolved
Something may be getting lost in translation. I am American so sorry for that. I am trying to put a factory into a map. I have it working as a placeable after the GC update. I copied the l10n_en.xml from the placeable to the l10n_en.xml that I have in the root folder of my map. My names all match from that xml to the mod xml. When I go in game though and pull up the GUI it shows that the l10n_en information is missing. It worked before the update. Is there somewhere else that the information has to go?