What is the "coolant tester" of which you post? Are you referencing a hydrometer which measures coolant concentration level (freeze point/boiling point)? If you tested concentrated Toyota Long Life Red it should have should tested higher concentration than the radiator AF. The latter should be around 50% concentration (~-34F freeze point). Now if it was the pink premix tested, should be close to the same as radiator.
As for when it should be changed, you should follow the OM recommendation for change. 80k miles ~11years...getting close I'd think.
As for SLL pink remix vs LL red, Topyota says they are compatible. However the red only rated ~2yrs/30k mi. vs ~5years/50k mi. for pink on subsequent coolant service.