Sycamore, sorry I don't see what you find confusing.
The prime pump and transfer pump cautions are on because in normal circumstances they should be extinguished, they bring to the pilots attention the state if the main tank switches and the prime pump switches.
Transfer pump off - warning on
Prime Pump on - warning on
Imho, your logic of having green lights on for when the Prime pumps are on (which would indicate all is well) is illogical.