Cannot duplicate the crash here. What OS version? I'm running 10.7.5.
Can you edit the gradient by dragging a swatch to the slider or option clicking a swatch while a slider is active?
It is crashing quite a lot with this file, I wonder if it is just an issue with the file itself rather than AI?
Is it native CC or can you work in CS5 or CS6 and see if it has the same problems?
Sometimes I will copy a section of a file into a new file and see if the problem persists.
I am guessing the studio I got the file from is not on CC, might be wrong, how can I check?
I did try the copy and paste thing with a new file, same problem with the gradient.
Just tried recreated the graphic with all the gradients, works fine, I am putting it down to a file issue.
I would just try opening in an earlier version. AI will warn you if it was created in a newer version.
Working with supplied files and be frustrating at best.