So here is your Langlands family in Scotland:
Scottish records are available from here.
https://www.scotlandspeople.gov.ukIt is free to register and search the index. Costs a small amount to purchase credits & download original documents.
John LANGLANDS (who became the grocer) baptism 24 Oct 1811 Dundee, Angus
Parents James LANGLANDS and Euphemia VALENTINE
Isobel GRANT baptism 25 march 1810 Tealing, Angus
Parents John GRANT and Anne WATT (married 19 Dec 1800 in Tealing)
John LANGLANDS (the grocer)
MARRIAGE on 12 Apr 1838 in Dundee, Scotland to Isabella / Isobel GRANT
1841 census Dundee Angus, Scotland
https://www.freecen.org.uk/search_records/5a140a60f4040b9d6eefe0f2/john-langlands-1841-angus-forfarshire-dundee-1812-?locale=en1851 Census St Vigeans Angus
https://www.freecen.org.uk/search_records/590273d8e9379091b10024e7/john-langlands-1851-angus-forfarshire-st-vigeans-1812-?locale=enTheir children born in Dundee Scotland:
Ann Watt LANGLANDS bapt 26 Jan 1839
Euphemia Valantine LANGLANDS bapt 4 July 1841; burial 14 Sept 1842
Isabella LANGLANDS born abt 1843
Marion (Mary Anne) LANGLANDS born abt 1845
John LANGLANDS junior born abt 1847
After 1851 the Langlands family moved to Cork, where more children were born (including your James and his brother William, ship owner).
Sometime after Isabella died in 1874, John moved back to Scotland.
I picked him up again in 1891 Scotland census.
1891 census St Clement Angus
John LANGLANDS 79 retired grocer, born Dundee
Marion LANGLANDS 46 Daughter, born Dundee
Barbara STRACHEN 5 granddaughter, born Dundee
John LANGLANDS (grocer) died in 1891 St Clement, Angus. Mothers maiden Name on death cert is VALENTINE. Looks like there is a will / testament for him on Scotlands People.