hajin wrote:1. Can I say 'ataried stones' for indicating stones in atari?
You can use the term, and it will be understood, but it is clumsy. In proper English, the '-ed' suffix is added to a verb, making it a past tense verb ( such as converting 'kill' to 'killed' ). It is not appropriate for other parts of speech, such as verbs or adjectives.
( Nonetheless, some English nouns do get used in this manner, such as the noun 'bicycle' being used to generate the past tense verb 'bicycled'. But even the most ignorant English speaker would not attempt to use the noun 'car' to make the past tense verb 'carred'. )
It is difficult to say what part of speech 'Atari' is. It was never properly introduced when it was brought over from Japan. Some treat it as a verb, such as 'to atari a stone'. Some treat it primarily as an adjectival phrase, saying 'in atari' as they would say 'in danger'. Some treat it as a noun, saying 'a ladder is a sequence of ataris'. ( The last two usages are consistent with each other. )
As best I know, 'atari' is a form of the verb 'ataru', and is a noun. But I am no athority on Japanese. If it indeed is a noun, then you should not treat it as a verb, and thus should not add the suffix '-ed' to it.
I recommend the term 'threatened stones'.
hajin wrote:2. Can I use ponnuki as a verb? ex) Ponnuki 5 white stones at the center
No! 'Ponnuki' is a noun in English, and is so beyond dispute. Do not attempt to convert it to a verb. We will have to kill you if you do.
hajin wrote:3. How should I call the state that black and white both are in atari, and capturing another means not in atari any longer? If I translate the korean term directly, it's something like a) interdependent atari b) related atari c) associated atari
Do you have any specific term for this? Or should I use one of them?
a) 'Interdependant' suggests that one being in atari depends on the other being in atari. This is not accurate. One group is in atari because of the presence of the other group, regardless of whether that second group is itself in atari or not.
b) 'Related' is vauge. It is not inaccurate, but is not particularly accurate either.
c) 'Associated' is also vauge.
I'd use the term 'mutual atari'. It is not great, but it is the best that I can think of at the moment.