You may want to make sure the new spark module is wired in the right way. The wires from the switch and the igniter for the same burner should be connected to the terminals with the same number.
...Does anyone know how the igniters know when the flame is lit?...
You can find such information in one of our previous posts: viking range professional
Here are the breakdown diagrams and Replacement parts for GE ZGU375NSD1SS | AppliancePartsPros.com