problem with $conf['i18n_variables']
You need to actually go to the page in the admin that updates the variable and edit it from the non-default language url.

For example, with site name, if you have one other language with 'es' as a path prefix you would go to 'http://example.com/es/admin/settings/site-information' and change the site name. Once you do that in another language it will create the variable in the i18n_variable table.

You will know you are on the right track when the element you want to update in the admin says "This is a multilingual variable"