I don't know of any, since the only Ploish version on Netscape's FTP server was 4.51... There were probably earlier releases, that I do not know.
Mozilla has been translated into Polish quite a few times, non-English builds can be found on Mozilla's FTP server under mozilla<release>/contrib-localized-builds
UserAgent: Mozilla/5.0 (Windows; U; Win98; en-US; m18) Gecko/20000929 Netscape6/6.0
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