Any news about this? For start there could be a define option in wp-config or in the theme with the default location of the tnp-composer folder
Something like
define('TNP_COMPOSER_DIR','/wp-content/uploads/custom-tnp-composer/');
Where we could keep and maintain our own copy of tnp-composer.
Of course if there is no define option it should default to /wp-content/plugins/newsletter/emails/tnp-composer
@Stefano what do you think?