Hi Cory
Coyne and Hoban are not all that common in Co Roscommon, so it should not prove to be a total needle in a haystack.
However, beware ... Coyne is an Anglicisation with variable translations such as Kane / McKeon /Owens (common to these parts).
Therefore HOBAN / HUBAN is the name to track (vis. Coyne or Kane or even McKeon).
e.g. Patrick Kain born 1818 in Scurbeg ELPHIN to Dennis Kain & Catherine Maguire
I agree with Roger though, you are probably looking for a parish for which no records exist. (Elphin parish records are pretty tight, so that there is no Hoban baptised here after 1811). HOBAN parish records are not revealing any alternatives for Coyne either.
So, you need to rely on land records as a starting point...
Look for Coyne & Hoban in the same parish (post-famine list here) and any alternatives
e.g. James Cain (labourer) & Mary Hoban of Dromduff (KILBRIDE civil parish of BALLYLEAGUE) baptising 1827-1871
Then for pre-famine records look to the Tithe Applotment records for Hoban; note in particular the following locations in the civil parishes of
Ballintober (2 townlands),
Cloonygormican (2 townlands),
Kilbride (1 townland),
Taghboy (1 townland).
BUT there's no corresponding Hoban parish match for Coyne (Kilcorkey, Killinvoy, Killukin Boyle, Kilmeane, Kilnamanagh, Kilteevan, Kiltullagh, Rahara). So that is why you need to consider possible spelling alternatives ...
Of the townlands containing HOBAN, only one lead emerges...
Thady Cain and John Hoban in Brierfield (civil parish of BALLINTOBER)
If you consider DNA testing as Roger suggests, the above information may help you pin down a point of origin quicker.
In the meantime, I suggest you join the following civil parishes on IrelandXO:
Ballintober
Kilbride
Kilteevan
Kiltullagh
Select all of them, when post your ancestors' details (as suggested by Roger). In time, something is bound to turn up.
Best of luck!