I said it wasn't plausible that an individual property in Dublin had increased in value by well over 500%, during a time period (1995 to 2019) when Dublin property prices in general increased by around 300%.
That's plausible. Assume the market increased 300%, your parents only outperformed by a third which can happen as relative prices of areas and property types shift.
The original claim was 700% from 95 til today (over double the performance of the market) which I don't think is plausible no matter where the property is.