1.- Create all custom WI entries in English language
2.- Publish customization changes
3.- In ARS Snapin open Configuration->Application Configuration->Web Interface (be sure that ARS Snapin is in Raw mode)
4.- Select Web UI configuration that corresponds to customized site
5.- Click Customization Settings->Current Copy
6.- Then open Current Copy advanced properties and find edsaWIStrings attribute
7.- Open edsaWIStrings attribute for editing
8.- Find the added custom WI entry by its value
9.- Copy the found string with its Res_ID and value
10.- Localize Language Files folder
11.- Open the folder with language ID that corresponds to the language you want ARS Web UI to be translated
12.- Restart IIS