I need help locating townlands mentioned in the Tithe Applotment books and interested in Cronin families from these townlands.

As you noted, Cronin's are thin on the ground in Cavan.  In Irish, the surname Cronin is Ó Cróinin, derived from the word crón, meaning “brown” or “swarthy” (almost all Irish names of Gaelic origin are based on the name, nickname, or description of an ancestor, real or eponymous).  According to MacLysaght’s “Surnames of Ireland”, the Cronins were a sept of the Corca Laoidhe in County Cork, and the leading family were erenaghs of Gougane Barra.  The surname originated in Cork, but is also now found in County Kerry.

I have a Cronin great-grandmother from Cork, so I've done a lot of searching for relatives there, and I was suspicious of the Cavan connection, so I searched in Cork.  There is a civil parish of Ballintemple in Cork, and in that parish there are townlands named Ballymacotter, Ballylanders, Ballywilliam and Ballyrobin.  I suspect that this is more than a coincidence, and part of your family history was in error.  Perhaps your ancestors moved to Cavan to find work during the famine, or afterwards.

In any case, at this link you can see all of the townlands in Ballintemple in Cork, and there are clickable links to each of those townlands, so that you can learn more about them:  https://www.townlands.ie/cork/ballintemple1/

It appears that the civil parish of Ballintemple is in the Catholic parish of Cloyne, and you can find the online parish registers for Cloyne at this link:  https://registers.nli.ie/parishes/0035

The registers go back to as early as 1786 for marriages and 1791 for baptisms, with some gaps, but there appears to be generally good coverage for the period you need.  You can download and save the pages, and search them at your leisure.

well spotted kevin45sfl!

Some of the Tithe Applotment record locations have been mix-indexed by  FamilySearch and the National Archives of Ireland - including including parish names which appear in seperate counties - Ballintemple civil parish Co. Cork included. It's mixed up with Ballintemple Co. Cavan and possibly others.

To access the correct Ballintemple Co. Cork Tithe records see the Tithe image browse tool, note the diocese is Cloyne, skip forward to see the various townlands mentioned - e.g. +10 gets you to Ballylanders

Ballintemple is actually in the Diocess of Cork not in the Diocess of Cloyne

Church of Ireland DIocese of Cloyne when the Tithe Applotment books were compiled, and as far as I can see Catholic Diocese of Cloyne (part of the Union of Cloyne) during the 1830s also.