I think the best would be to directly increment a variable with the button.
Create a Variable action list with 6 actions. For each value of the variable between 0 and 4 create 2 tasks, one for setting the timecore source to a specific input, and the other one to display the source name on the led screen.
Use the last action, to loop the. variable value when it reaches 5 then set the value back to 0.
And also create a system action list to set the variable to a value in the 0-4 range when the timecore starts.
Enjoy,
