Kilcornan is the name of both a civil parish (which developed into an administrative district) and a Catholic parish. The boundaries of the two types of parishes do not always coincide, but in this case they appear to be roughly the same.
You can search the parish register for the Catholic parish online here: https://registers.nli.ie/parishes/0874
You can see a map and some more info about Kilcorrnan at this link: https://www.logainm.ie/en/1556/
Further information is normally available at this link: https://www.townlands.ie/limerick/ but that link is not working at the moment (it stops working from time to time).
Croagh is not in the parish of Kilcornan, but is a bit further south (as you can see from the interactive map at the parish register site mentioned above), so perhaps the family moved at some point. The time period discussed above was just before and also during the famine, and people did move around then.
Croagh is also the name of both a civil parish and a Catholic parish with roughly the same boundaries, as well as a townland within those parishes. Townlands are the basic address unit in most rural locations, and that is the location usually given in a baptismal record, though marriage records often omit it. Townlands varied in size and in the number of residents (which gradually declined in most cases, as the famine and emigration took their toll). Note that the anglicized version of a townland name may have changed over time, since the priest or official was trying to write the Irish name in a way which he thought represented its sound (or its meaning, in some cases). The spellings (and even the boundaries, in some cases) were not standardized until the late 1800's.
You can search the parish register for Croagh at this link: https://registers.nli.ie/parishes/0880
And you can see a map and more info about the townland of Croagh at this link: https://www.logainm.ie/en/32048
and also at the townlands.ie site mentioned above, when it is working.