Sorry I did not see the 2019 reply. Here’s a link to the 1834 tithes in Carncastle. They list John Miller in Ballyhackett:
http://www.irishgenealogyhub.com/antrim/tithe-applotments/carncastle-parish.php
They are also on the PRONI website where the exact size of the farm should also be listed. The measurements will be in Cunningham acres (a measure popular in Scotland and the north of England). Multiply by 1.62 to get standard statute acres.
If you go to Ballyhackett on the Griffiths site
http://www.askaboutireland.ie/griffith-valuation/index.xml
you will see that in 1861 there were 6 farms (though two of them were rented by the same person). Thomas Shaw had approximately 41 acres, Henry Shaw had 59 & 142, Robert Stewart 44, Rev Carmichael 33 & John Barber 19. (These measurements are statute). What you may be able to do is compare who was renting in 1834 with the names in 1861. That may tell you which farms have not changed hands and so can be excluded. You might also be able to work it out by comparing the acreage (converting the tithe acreages by multiplying by 1.62). That’s not an exact science because of course people acquired and lost land, so it’s not guaranteed they are all exactly the same 30 years later. But it might help. The farm occupied by the Rev Carmichael is probably “Church farm” which is beside the Church of Ireland. You can probably exclude it as it will be part of the church’s property and occupied by the incumbent. The farms are all on either Sallagh Rd or Ballymullock Rd, just south of Cairncastle. There are maps in PRONI and in Ballymena library which show the exact locations of each of the Griffiths farms, so if you can pinpoint a specific farm, then you could narrow it a bit further. (Though both the library & PRONI are closed at present). But that said, they are all on either Sallagh or Ballymullock Rds.
From general experience, it’s unlikely that the current occupants of these farms will all know who lived there in the 1840s.
With regard to where the family might be buried, I do not know if either of the 2 Presbyterian churches has a graveyard, but if they do, try there. Failing that try Cairncastle Church of Ireland. It’s far from guaranteed that there will be a gravestone. Not everyone could afford one.