We've updated the configurations. For values that need to be different between sandboxes, you can now create your own configurations. You give the configuration a name and a value and whenever you need them you can create a new variable of the configuration kind to fetch the value.
Custom configurations for values that need to be different in sandboxes
This way you are able to safely update the values for each environment and you don't need to use global variables and/or the is_sandbox in expressions anymore.
