the gearbox clutch packs dont need to be replaced, they are not a regular service item, only thing you can replace after dropping the pan is the filter inside, at 50k I would first drain the fluid from the drain bolt about 3 litres would come out and inspect it if it smells burnt or is brown I would then drop the pan and change the fluid and filter as well as put a new original gasket not silicone, or You could also flush the ATF from the cooler line but have to be expert in that. If the ATF is still pinkish and does not smell burnt I would change it at 60k or 70k km, as the Change interval is 70k for ATF. It uses toyota WS fluid.
at 50k you can consult your owners manual as that has a list with dates also given when what should be changed. I would have the brake pads inspected unless you have recently changed them, make sure silicone grease is on the slide pins noting else, Change the sparkplugs oil filters etc but do not mess or bother to clean the throttle body. At 50k I would not bother with the fuel filter either if its running fine, its interval is given longer in the handbook. I would have scanner connected and see all the live data especially fuel tirms AFR sensor values etc, any problem with catalytic convertor or anything would show up there, though I dont understand how people manage to choke their cats especially hondas which are only two-three years old, I have a 2006 Altis as well and never needed so called catalytic convertor service etc so unless you are facing severe issue or there is a problem with the values on the scanner do not bother with the catalytic convertor as well.
rest is all checks, check the suspension the ball joints tie rods, bushes, boots etc for any play or cracks, measure the thickness of the rotors using a vernier caliper to see if its in specs, check the tires etc.
Half of stuff that toyota dealerships say in thier service packages are wrong and dont even match with the owners manual, they would attempt to do some stuff that you dont need while missing out on some stuff that you do need, so if going to 3S tell them to forget about their maintenance plan and follow things you said.