http://landedestates.nuigalway.ie/LandedEstates/jsp/estate-show.jsp?id=3464
reports that Mount Pleasant was advertised for sale in June 1870.
I wonder if that was when it was bought by the Ronaldson family.
Thos. Dowling Ronaldson of Mount Pleasant married Elizabeth Jane Scott of Ballyvillane in Ballymackey Church on 18 Aug 1891. They were living in Killowney Little with their two daughters in 1901.
In 1906, the Cox family advertised another house named Mount Pleasant for sale, this one in the townland of Clarefield in County Clare.
By 1911, the Ronaldsons had moved from one Mount Pleasant to the other, possibly attracted by the name.
The Tipperary Mount Pleasant no longer stands (per landedestates.ie), but the Clare Mount Pleasant is still an imposing ruin, with magnificent views over Scattery Island and the Shannon Estuary.
I am happy to tell you that Mountpleasant house still stands. I know this because it has been the homeplace of my family since the 1940s. A Family of solicitors in Nenagh, the Hodgins' owned the house until it was sold to my great grandfather, John Dunne of Middlewalk in the 1940s. My grandfather Rody Dunne then lived there with his wife and raised a family and now his son continues to live there. So yes it still stands and what's more it is still lived in.
During the time of its previous residents the original house was extended to double the size. My grandfather found the house too large and that the extended section had too many issues and so the extended section (which faced the front) was knocked and used to fill the basement. So what still stands today is the original original building.
Hope this helps someone to discover more.