In server connect expressions must always have the curly brackets around them.You can always recognize the fields that accept expressions by the 
. If you don’t have the curly brackets arround them they are being seen as normal strings.
I agree that some extra feedback would help in some cases and we should provide more inline help.
Without documentation it is probably difficult to understand what certain properties do, the Global Name in the Set Value is a good example for that. The property is to assign the value to a global variable. When you are in a repeat it will have a local scope inside it and the Set Value will set the value in that inside scope and not update the one outside. With the Global Name you can set and update a variable in the global scope. This is only important for the repeats, conditions and the while loop don’t create a new scopes.