To do that you can use the fourth – callback argument off the exportData method. You can pass a callback which accepts the data as an argument and from there you can loop through the objects and change the property name then export the data manually.
I’ll take a look at it, but this seems very hacky. If you’re going to have certain field names invalid, then giving mapping options would be a lot better. That way I won’t have to hardcode it in my app and instead have it in my DB.
Or, you could make those system names very unique, like I suggested. “$” or “-“ along those lines.