Hmm if it does always flow to the cooler that makes a bit of sense. Just looking at the block, where the thermostat is located & the channels it connects to id love to see a diagram of how the flow works inside.
OK think i have it sussed, stole this pic from GTR.co.uk - my one doesn't have letters on the filter block.
F = inlet from outer connection of sandwich plate
E = return to center of sandwich plate
C = in & out cooler connections
Sound about right?