The Five Eyes Countries as I understand it relates to sharing intelligence about terrorism rather than about what individuals do as regards over staying, or in their daily lives
But yes you must seek proper advice from the relevant authorities including the US State Department if that is where you now live. No one on this forum can give you binding legal advice, just opinions which will be worthless at the border.
If you are now back in the US it would sound as if you were never recorded as an over stayer 20 odd years ago- otherwise surely you would have been stopped on returning from Cyprus or indeed when you first re-entered the US. Thus there may have been nothing to share with other countries.
The real risk is that if your original over-stay is unknown, by asking the questions now you may cause a case to be opened which never existed. My memory is that US border control was less onerous in the days of paper- recorded a lot less- than now in computerised days. But that may just be my memory. Wasn't it landing and departure cards in those days?- so if you went into one city and out of another (like me) joining the dots would not have been easy. I went into Denver and out of LAX, and into Chicago and out of SFO- or something like that.
