I cannot find a birth registration for James or Louisa.
From the census, James was born before the 1871 census, but until you find the 1871 census there is no evidence they were in Cardiff as claimed.
These almost fit for Robert
Robert Coole . mmn Shea
Jan-Mar 1877 . Bristol . Volume 06a . Page 47
Walter Coole . mmn Shea
Jan-Mar 1879 . Bristol . Volume 06a . Page 39
Walter Coole . 0
Jan-Mar 1879 . Bristol . Volume 06a . Page 30