Thanks for your fast answer.
My problem is different, because it fails also after configuring 1G of memory limit.
Debugging a little bit your plugin it seems that add_languages() fails with the first language (in my case English), and the rest of languages migrates without problems after the unset( $GLOBALS['wp_settings_errors'] ); sentence.
If I add this sentence to the beginning of the loop all the languages are migrated without problems.
Again, thanks indeed for your support and plugin.
