Does s2member support multilingual custom fields using another plugin like qtranslate?
This from qtranslate's site:
...for dynamic texts (comment text, blog entry text), I suggest using qtrans_useCurrentLanguageIfNotFoundUseDefaultLanguage() instead. Use something like this:
if(function_exists('qtrans_useCurrentLanguageIfNotFoundUseDefaultLanguage')) $output = qtrans_useCurrentLanguageIfNotFoundUseDefaultLanguage($output);