I read the commentary different. I read it as stating that the abandoning play (not a pass but is commonly referred to as a pass) IS a declaration to stop. I don't read this as saying that a player may pass to declare the stop of the game. The concept of an abandoned move (着手放棄) is not the same as a pass (パス) otherwise the rules designers would have just said pass.
How you, or DeepL or whatever it's called, read it is irrelevant. It's how the Japanese read it that matters. A couple of points that you seem to be missing linguistically:
(1) sengen - you have latched onto one the word 'declaration' and sometimes seem to take a typical English nuance: that something has been unilaterally decided. But, whichever way you take it, what is going on in the Japanese is simply that something is being enunciated, made known. Use a Japanese dictionary. Kojien, for example, will tell that it refers to the case where "an individual, organisation or state expresses [hyoumei] its own intention, claim, plicy or such like to outside world." It is a unilateral action.
(2) In comment 2.2, deari is in the continuative form, so the following "if" applies to that clause as well. The English offered by Pio omits and 'also' - if the opponents also makes pass - so the result in the next clause comes from a
bilateral action.
(3) The result just mentioned (cessation of play) is described by using the verb phrase 'to naru' (i.e. not 'dearu'). ... to naru (becomes) implies 'changing so as to be'. In other words, the change of state (from ordinary play) takes effect only after the two conditions (Pass 1, Pass 2) just mentioned have been met.
(4) You are fond of the phrase 'abandoned move'. That sounds strange to me. What the Japanese houki refers to is
relinquishing the right to put a move on the board ('putting' is what chaku implies). It is not an assertion that play is abandoned as in "match abandoned". Chakushu, incidentally, is a go technical term here. In the normal language it means 'to start'. In a go technical dictionary it is defined as 'Playing a stone. Putting down a move."
(5)
The concept of an abandoned move (着手放棄) cannot be the same as a pass (パス) otherwise the rules designers would have just said pass.
No, because "pasu" is a colloquialism and this is a legal text. In real life next to nobody would say chakushi houki, a very stilted phrase. It is, however, required in a legal context, if for no other reason than to show which of the many senses the borrowing pasu is being used in (and the go sense is by far one of the least common).
(6) Article 2 allows plays to put stones (chakushu) on the board alternately. Comment 1.1 helpfully tells us that the alternation of putting moves on the board is a RIGHT, i.e. not an obligation. That is, on your turn, you can do something else. I have already told you that the debate about whether a board move is a right or an obligation raged for many years in Japan (that is the context, but no context is really needed for this point). In J89 the Nihon Ki-in and Kansai Ki-in nailed their colours firmly to the mast: putting a stone on the board is a RIGHT. In America you have the right to bear arms. That doesn't mean you
have to go out and buy a Kalashnikov.
Thinking more about this, it reminds me of Japanese grammar and formality, which I am trying to learn. In Japanese you can make a very long statement with many details while providing the sufficient level of formality for the situation. But when the context is clear, you can drop a bunch of words, and when formality is not required you can do away with even more works. And in Japanese writing you can even drop the hiragana from the kanji. Of course, many languages can drop context, but Japanese also can drop formality.
I think it's best to draw a veil over this paragraph and wait until you have learned some more Japanese. The rules text is in standard dearu neutral form as is usual for legal and technical texts, and I've been translating that kind of stuff for part of my bread and butter for over 50 years. And furigana is used only for children's books, names or rare kanji. It has nothing to do with formality. Reading characters is not very hard if you are a grown-up Japanese.
(7)
So, it seems to me that when White plays, Black play, White passes, and the context is that White is declaring that they want to stop the game because the game has arrived at a plausible end-state, then black may indeed play at once without the formality of passing and then demanding resumption before his play. It seems more polite and more elegant to not demand the formality.
My apologies if I am misreading what you say, but let us assume instead that they do replace the toujours la politesse and elegance with formality (although in Japan formality is usually a necessary part of politeness). The actions would then be White plays, Black plays, White passes, Black passes, Black demands a resumption. You then have Black making first move in the confirmation phase. But that is not allowed. The person making the request for resumption has to let the other side have the right to the first move in the confirmation phase, no?