I think here you need to look at how easy it would be to add another language version to your system. Variant 1 would entail adding more fields to your table. Variants 2 & 3 require no structural changes to the database, just the additional of data. Personally I would favour Variant 3.
Also you might want to consider adding another table for locale info, which you foreign key link to in your thing_loca table. Depends on whether you want further info on the language in question, eg. dialects, versions of a language (UK english, US english).