Use the bone names, instead of the sprite names. The names can be seen if you click the hierarchy tab, or expand the timeline view in Spriter. in this case, in C2 change the name of the parent and child to "bone_000" and "bone_001", respectively.
Ahh! That's it. So I need to reference the bone name... I'm really dumb hehe
Thank you very much for the help.
But, seriously, it would be awesome to have a formal tutorial on this subject. That's a really cool feature.
Just one more thing... there is a place where I can download always the last release of the c2 plugin?