It's unlikely to be a C2 bug and probably is a problem with your events, since when you delete the global variables it will remove the conditions and actions that uses those.
Also, I didn't notice any true difference between what happens with or without the variables.
At last, the capx is far too complex for a bug report.
Try to reproduce the issue in a simpler capx.
Also, if global variables were really a problem, with every users using them, there would have been more than one bug report on the issue and far before you would have done yours.