You can use the attached ""Utility - Strings - Extended"" object. It's a basic object that basically uses a calculation stage to change the special characters of a string to something that could be interpreted by the Global Send Key Event.
For example, if you give the object an input like :
this is my string %25 of $100 = $25
The output would be:
this is my string {SHIFT}25 of {SHIFT}100 = {SHIFT}25
And then you can use this output for the Global Send Key Event.
I'm sure there is a better way to do it, but this does the trick.