It is strange, normally the typical tuning of a cuatro is A D F# B with the particularity on the B string, tuned an octave lower.
The GCEA tuning is not very usual for the cuatro, even though it could be tuned that way, but the important thing is to maintain the octave lower on the last
Here's a video I made playing the venezuelan cuatro:
http://www.youtube.com/watch?v=TSoey34VtQQ
And here are two links in english about the venezuelan cuatro:
http://camburpinton.org/eng/
http://tucuatro.com/en/
Check them out and let me know what do you thing about this instrument