This depends on how you’re displaying the logo on mobile.
If you’re using the Mobile Header option, you can adjust your function to include its logo:
add_filter( 'option_generate_menu_plus_settings', function( $settings ) {
if ( ICL_LANGUAGE_CODE == 'en' ) {
$settings['sticky_navigation_logo'] = 'your english logo image URL here';
$settings['mobile_header_logo'] = 'your mobile logo';
}
if ( ICL_LANGUAGE_CODE == 'jp' ) {
$settings['sticky_navigation_logo'] = 'your japanese logo image URL here';
$settings['mobile_header_logo'] = 'your mobile logo';
}
return $settings;
} );