Exactly. I mean, it's fun to have all the symbols and such, but it's not really translating it into actual ancient Egyptian. A few years ago, my mom gave me this thing that she ordered that claimed to translate a name into Egyptian hieroglyphics (I used to be a huge Egypt geek every sense I saw this program back in the 1970s about King Tut). Anyway, she gave it to me and told me what it was. I had assumed that they had taken the actual translation of my name (which loosely translates are "warrior") and then used the hieroglyphic representation for that word. Instead, it did exactly what the Discovery Kids site is doing.
If you want to use hieroglyphics in your game, there are bunch of good books on the topic. But, sense your players will never know the difference, it's probably just easier to use a site like the one above.