just a tip for others running into similar issue I did.
When you're using Typesetter CMS in own language the RSS Feed plugin complaints about language missing. This is because of a check in code that checks for language file existence and in case it is missing a msg is echoed before english is used as default language. So, to get rid of the msg you'd want to copy the en.php file in same folder, name it the locale of your used language ie. pl.php or nl.php and translate the contents into your own language.
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