I tried the search option but I don't see where in the Bethesda CK you would add localization.

I am trying to help an author with his file and there are localization strings. They don't work as far as I can tell. I renamed the items, which in turn updated all the links to the items. I added a name that makes sense and a description. However, it says LOOKUP FAILED! in game for the items.

magicmoonsp_English.DLSTRINGS
magicmoonsp_English.ILSTRINGS
magicmoonsp_English.STRINGS

I also speak Spanish fluently and could add strings for that as well. Where is this done I can't find any topics on it at the creationkit website and I don't see any videos with mention of it. The videos say 2:34 basics, 3:40 adding armor but there is no mention of localization.

Where are the options for localization strings? I would prefer to NOT use third party programs. However, even if I do how do I add the strings to the armor item so that Skyrim can find them?