It's very realistic to change Dragon Challenge cosmetically, ESPECIALLY now with how financially successful both lands are. If they changed Unicorn into Hippogriff, why not make the Dragons more accurate, especially since the Hungarian Horntail is already present in Forbidden Journey in its correct form.
I personally think it's a big issue, and might not be a big issue to you because you aren't a Potter fanatic. It just bothers me that with all the attention to detail put everywhere, that they couldn't change the cars themselves. I'm sure back then they had to make budget cuts. But I'm talking about now/the future. With the direction Comcast is moving to, I think they should upgrade Dragon Challenge esthetically.