Toyota WS (World Standard) Transmission Fluid is the current fluid specification for most every modern Toyota Vehicle. Toyota markets it as a "LifeTime Fluid" much like other manufacturer's market their own Transmission fluid as "LifeTime", what exactly they consider "LifeTime" I have no idea whatsoever. As I have mentioned on the forums before, out of all of the fluids in a modern vehicle the transmission fluid is the LEAST likely to be "LifeTime" because it does the hardest work out of any fluid in the vehicle. At best its a long life fluid and its something I and other people have maintained vehemently.
In my personal experience I have found WS fluid holds up to about 100k pretty well under normal driving and a fluid exchange or "flush" done between about 80-100k is a good rule of thumb. This is based on my personal experience, the experience of my dealership and its mechanics, other fellow mechanics, and fellow members on the forum. In fact, many dealerships sell transmission fluid flush services at 100k for Toyota vehicles because this is also their learned experience.
Also who are you having do the inspection? Because almost no dealer is going to actually inspect the fluid condition without you directly asking them to do it. It has a pointlessly complicated and overly technical method of checking the fluid level as there is no dipstick.
If you want to cover your bases, you can tell the prospective buyer "The transmission fluid is considered "LifeTime" by Toyota, but many people recommend replacement around 100k as a conservative measure, which to my knowledge has not been done."
Now, these transmissions aren't as finicky as older units where at 100~150k you flush them (after never being done) and they fail; so I would also impart that to the prospective buyer, but I wouldn't let the vehicle go too much longer without a flush out of my personal opinion.
