Hi,
For sure C2 is a good choice but depends how she likes the interface, cause at that age, the interface is everything for her. And C2 can be customized to be more colorful and cute, but still has the Windows 98 kinda of feel, which might not be so great for her. Present her the idea of other visual programming software(Scratch, Stencyl,Game Gdevelop which is similar to C2,BuildBox, GameSalad which is designed for kids and has a great glamour look) and add C2 between them, see which one she picks.
However even if C2 is easy to learn, when your 7-8 years old you like to build and play stuff, i wold not yet push her to Game development and wold wait till shes like 10-12(thats the time when they might get addicted in game playing and not pay attention to school), reason why, once you start developing games, it takes away the fun of playing games, cause you build an idea of how games are made, and then its like you know the pattern of the games in advanced, which for me is not fun. It taken the fun out of games atleast for me, a grown "ars" man that loved to play games, now im am like ehm... another one.
If you are not worried about taking the joy out of games for her and want to introduce her to Game Development, then C2 is one good choice. Not sure how Kids see it, im not a teacher, better ask a Teacer/Person who teached C2 to kids and what where their reaction, and how fast they where learning it. Take a look at the Teaching C2 section Maybe you find your answer around there.
I hope my answer was something you where looking for or atleast give you a different perspective to the problem!