"No one is speaking anything here."
Translation:यहाँ कोई कुछ नहीं बोल रहा है।
First of all the Hindi sentence is literally something like 'Anyone is not speaking anything here'.
Hindi sentences follow the subject-object-verb order. The verbs (the main verb along with the auxiliaries) always occur at the end of the sentence so बोल रहा है comes at the end. The negation नहीं comes directly before or after the verb it negates (so बोल नहीं रहा है is also right). The object- कुछ (anything) comes before the verb and the subject (कोई- anyone) comes at the beginning of the sentence. यहाँ (here) is used here more like a noun rather than an adverb so it can come before or after कोई.
I'm not sure what distinction you're trying to make. Could those statements be paraphrased as "the conversation has paused" and "we're expecting so-and-so to speak, but he isn't"? If so, then you might make your distinction by being explicit about whose speech you're waiting for and using he/she/they instead of "someone".
I was pretty cryptic. As a native English-speaking novice to the language, the sentence "कोई कुछ नहीं बोल रहा है" seems to say "someone is not saying anything," which is like "everyone is speaking, except for one person," which is almost the opposite of "no one is speaking." I've gotten used to the idea that this is just how things are done in Hindi. An answer to my question, I think, is "सभी लेकिन एक बोल रहे हैं." Thanks.
You are right that Hindi negates the sentence 'Somebody is speaking something' as 'Anybody is not speaking something' = 'Not even somebody is speaking something'= 'Nobody is speaking anything' rather than 'Somebody is not speaking anything'.
Your last sentence would be सिवाय एक के सभी बोल रहे हैं। (सिवाय is 'except'. लेकिन is 'but').
You can also say कोई एक कुछ नहीं बोल रहा है for 'Someone is not speaking anything' though it might be more colloquial.