There is a civil parish named Croom in Limerick, about which you can learn more at this link:
https://www.townlands.ie/limerick/croom2/
At that page, there is a list of the townlands within the civil parish, with links to more info about them, and you'll note that there is a townland also named Croom. When you go to the page for each townland, there are further links to records such as Griffiths Valuation (mid-1800's). The records for the townland of Croom do show one Cronin tenant/landholder, a Denis Cronin, at this link (there are no Coney's shown):
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=doNam…
Civil parishes are administrative districts, and do no always have the same names or boundaries as the local Catholic parish, which may be larger and contain some or all of several civil parishes. There is a Catholic parish of Croom, but its boundaries appear not to be exactly the same as those of the civil parish. The Catholic parish records which are available online for Croom are found here:
https://registers.nli.ie/parishes/0881
Those records go back to the 1770's for marriages and deaths, and the late 1820's for baptisms, so you ought to be able to find some of the people in your list, if that's their home parish.
The people you listed appear to be named Coney or Croney, not Cronin. According to MacLysaght's Surnames of Ireland, the name Coney is rare, and is usually a variant of the name Cooney (Ó Cuana in Irish). That surname apparently originated in Ulster, but many of them moved to Connacht, and the surname is now found in many places in Ireland. MacLysaght has no info about the name Croney, but I suppose it might be a variant of Cronin.
If you're sure that the family was named Cronin, then that surname (Ó Cróinín in Irish) originated in the next county to the south, Cork, and is mostly found in Cork and Kerry (though also to some extent in Limerick and other nearby counties). There is no "Croom" in Cork, but there is a parish named Macroom, which is more or less right in the heart of Cronin country. The Catholic parish records for Macroom go back to 1780 for marriages and 1813 for baptisms, so they might be worth a look. You can find them here:
https://registers.nli.ie/parishes/0077