You changed nonaphobia to enneaphobia, unophobia to henophobia, centumphobia to hekatophobia, and duophobia to dyphobia. Hybrid words also exist. Why can't tetraphobia be called quadraphobia or pentaphobia be called quintaphobia? People aren't really familiar to ennea- anyway. I now regret changing Miliphobia to Chilophobia, and Vigintiphobia to Iscoaphobia.
Because I use Greek prefixes and couple other reasons. Nona- is latin and the other user suggested me to change that to ennea- and then I accepted his suggestion. I used to title unophobia until I found out that unophobia is the fear of being single, so I changed that to heno as it is the ancient Greek word for one. Centum- in centumphobia is Latin for hundred, and hekato is Greek. Although the former is also Greek, I changed from duophobia to dyophobia to have fancier pronunciation to go along that 'di' not 'du' is the usual prefix to use for sets of two, such as dioxide. Tetraphobia is the more common term for fear of four than quadraphobia because we more tendingly use Greek roots to go along that phobia is from the Greek word.
Triskaphobia is based from the well-known triskaidekaphobia, fear of 13. Triphobia is as alternate term as said in triskaphobia page. Some people may choose to use alternate term as the personnel usual term, like you.