Hi Christine
It's always hard to give people a snapshot of your hard researched work

You certainly have gone back stage by stage. I think where you might be going slightly astray, through no fault of your own, is only down to possible misreporting of Robert b. 1830 father's name on his death certificate....not surprising given his grand age at death.
As far as I can make out, you have:
1. John Sutherland b. 1881 - Parents Robert Sutherland b. circa 1854 m.1877 Grace Himsley. You have Robert's marriage and death certs confirming his parents.
2. Robert Sutherland b. c. 1854 in Dunfermline - Parents Robert Sutherland b. 1830 m. 1851 Ann Finnie. Robert b. 1830 was born in Glasgow and was a shoemaker (like his father- from his death cert.).
3. Robert b. 1830 in Glasgow - Parents from his death cert show as George Sutherland and Mary Short. Father George is showing as a shoemaker.
You have found two Old Parish Register entries (pre the start of official registration in Scotland the entries you have are from these registers and as such look different to the standard BMD certs post 1855). The information that is included on the OPRs is a bit of a lucky dip - mostly no more that single line entries with very little info as you have found.
~ George Sutherland, a shoemaker, and Janet Dickson married in Glasgow in 1832
~ Robert Sutherland, no occupation given, and Mary Short who married in Glasgow in 1822.
I think this may be where it is all going belly up! I cannot see anything more for a George and Janet on record.
However, for Robert and Mary Short, the following children show, all born in Gorbals Glasgow:
Janet 1823
Mary 1825
George 1828
Robert 1830
George 1832
Penelope 1835
I can see an 1841 Census entry in Glasgow for Mary mother with some of the children, but no Roberts (father or son) which is a pain for verification. By 1851 Robert b. 1830 is in Dunfermline working as a shoemaker.
The daughter Penelope (being a relative unusual first name) was easy to find on deaths. She died young:
1872 SUTHERLAND PENELOPE 35 GOVAN AND GOVAN CHURCH GLASGOW CITY/LANARK 646/01 0652
From her death cert, both Mary and father Robert show as deceased (I think it is looking like pre 1855 from the censuses and death searches). More importantly, father Robert is showing as a
shoemaker. Penelope died at Govan Poorhouse - another avenue for you to follow up if Poor Relief application records remain for her (could provide additional info/background on the family).
Additionally, from the children showing for Robert b. 1830 and Ann Finnie, you also have first born son called Robert born c. 1854 and first born daughter called Mary after both Ann Finnie and Robert's mother. The George son they had later in 1862 could well have been called after Robert's brother (2nd George born b. 1832). It may be that George was the name of Robert b. 1830's grandfather which is where the confusion on names may have arisen.
This by the way is Ann Finnie's death entry - father does show as Thomas as you thought and mother as Mary (no maiden name):
1887 SUTHERLAND ANN FINNIE F 56 DUNFERMLINE /FIFE 424/00 0269
...a bit of a long post

hope it makes sense

Regards.
Monica