WordPress multisite How to apply PO translations to common core files shared by all language sites
I am using Multisite to create a Spanish version of the site as a subdomain. The wordpress default po files include the translations I need, and they are being successfully applied to the strings in login.php, but for some reason, the translations aren’t being applied to the strings in wp_signup.php, ms_functions.php, and user-new.php, strings that are crucial to the registration process. My guess is that these files that are shared by all network sites are somehow not being notified that the user originated from the Spanish language site. I know that as a problematic workaround, I could use php to detect the language of the user’s browser, but I don’t want to do that. I am a "fish out of water" with wordpress. Can someone shed any light on this issue?