Well, I agree that the Japanese rules are ambiguous. I’ve even created an entire thread diving into various technical cases. See Odd Cases 🤔 in the Japanese Rules
Frankly, it’s a bit insulting for you to assume that I have a mistaken impression or have taken only a superficial glance at these rules. However, your mistaken impression of me seems reasonable given that you’ve only taken a superficial glance at these forums.
However, what I’m trying to point out is that you won’t find universal agreement about which rules are “ambiguous”. There will certainly be many that assert otherwise for the Japanese rules.
Among the various rules sets that you are familiar with, which do you consider to be unambiguous? I think that this topic could generate a significant amount of debate.
I think this is also an historical question, which is tricky for me to answer. I’m not so familiar with all of the many rules sets that have been written down over the many years of history. It’s hard to say what even counts, if some written forms did not gain much prominence or were largely forgotten by time.
I would venture to guess that perhaps some form of stone scoring rules must have been written down at some point over the past few millennia, perhaps earlier than many other modern examples.