Well spotted! It’s a simple typo. It actually occurs in the Canada 1916 and 1921 files as well. The fix is easy:
For the 1911….
Open the file kiwitrees/library/WT/Census/CensusOfCanada1911.php
Change line 56 from:
new WT_Census_ColumnNationality($this, 'Nationality', 'Racial or tribal origin'),
to:
new WT_Census_CensusColumnNationality($this, 'Nationality', 'Racial or tribal origin'),
The files for Canada1916 and Canada1921 are in the same location, and the change is the same apart from a slightly different line number and (of course) the different year in each case.