9.G definitely needs to come with some references, cause his gardening references simply don't make any sense.
My guess is that the aircraft simply aligns the IRS heading with the localizer course no matter what the calculated FMGS track is. And that we only need to check if the ILS course is displayed correctly.
The FCOM does not provide any more information than this.
The notion that the aircraft is not following the correct localizer (ground) course because the calculated track is off is simply ridiculous. The aircraft adjusts the heading to maintain the localizer course and is thus on the correct ground track.