Your example is not an example of actual Firefox failure mode: If I encode your text as ISO-8859-1 and run chardetng on the bytes, it says ISO-8859-2. It’s generally unlikely that chardetng would misdetect ISO-8859-2 Polish as windows-1252.
When you claim that something isn’t working for you (and it’s completely plausible that you have encountered a case where chardetng doesn’t work for you), it would be polite to post the actual failure and not something that’s not an actual example of failure.
When you claim that something isn’t working for you (and it’s completely plausible that you have encountered a case where chardetng doesn’t work for you), it would be polite to post the actual failure and not something that’s not an actual example of failure.