This is a legacy problem from one of the original contributors.
The rule is that the definite article after a vowel becomes 'r.
Thus this sentence should have been entered as .......caru'r GIG.
When the mistake was spotted we couldn't delete the original, although that is fixed in the much delayed revised course.
Thus your suggestion is not the standard correct answer, no problem with the abbreviation though.
However since you have worked so hard on the course it's now added, :-)