CircuitSmith…just as another data point for you.
I just went and checked the Factory Service Manual for a 1996 Toyota Corolla. They list as manual transaxle oil lubricant: API GL-4 or GL-5 SAE 75W-90; 2 quarts total.
So, after all perhaps you are indeed OK with the GL-5 you put in. However, I am not sure if the tranny model they used in your 2006 is the same is the one in the 1996. They do not specify anywhere the manual tranny model/code for it.