The report may be misleading. It states that quality of Honda Civic has gone down, that is not true at all. The quality of Latest Gen. Honda Civic is way better than the initial Civic of the late 1970s. But What has changed is the margin of quality improvement.
Honda Consumers had this extremely high expectation from Honda cars, specially in US and Europe, that now they what they are seeing is not matching those very high expectations from Honda. That does not mean Honda Civic is a bad car now, but simply means that others like Hyundai have stepped up their game alot higher, that now car makers like Hyundai's Elantra now have same impression as once Honda Civic used to have.
Civic is still a very good car, but needs to keep improving their quality, from being Better to be Best as they used to be in the past, with fewer market players.