I believe that is the archeological finding, yes. Someone may know more about this than me, but all of the exposed buildings in the pilgrimage sites date from long after the Buddha, usually perhaps the Gupta period. It’s possible, of course, that the later buildings were made on top of earlier constructions and maintained their proportions; we know that this kind of thing did happen a lot in ancient India. But we can’t really know for certain.
It still has historical significance as a record of that period, but sadly there are no direct archeological remnants known from the Buddha’s time.
In my opinion we can’t. There is no reliable standard for the sugata measurements, all we have are a series of informed guesses. If someone wants to take them as a rule of thumb, well okay, but it shouldn’t be considered as a mandatory rule.
It’s okay, but I wouldn’t begrudge a monk or nun a little more space!
I haven’t followed the Chinese arguments in detail, although I do have a vague memory of disagreements in the Chinese Sangha too. But translating from an unknowable Indian measurement via a method of unknown reliability into a (possibly also unknown?) ancient Chinese measure seems … optimistic? Do you have any references on it?
When I was in Bodhgaya some years, ago, I was involved in discussions about setting up a bhikkhu training center, and thus learned something of the way land area is usually measured by the katha.
I know what a nightmare it is to rely on a non-standardized unit, especially trying to understand it as an outsider, let alone an outsider from 2500 years in the future.
Forgive me if I fear our chances of satisfactorily understanding the sugata measurements lie somewhere in that long wasteland between zip and nill, where we are guided only by the bones of the former travelers. 