User activation success page localization problem
When you register/save the user you need to set their preferredLocale, so Craft adjusts the verification URL sent with the activation email accordingly. Craft uses the primary locale for a user who doesn’t have a preferred locale set.

You can do this using a hidden input field in the registration form, or via a users.beforeSaveUser event listener.

&lt;input type="hidden" name="preferredLocale" value="{{ craft.locale }}"&gt;


Once your users have a preferred locale set, your localized activateAccountSuccessPath config should work.