C. S. Bartholomew wrote:Who is speaking and what do they know?
Smyth's text puts 613-14 into the mouth of τοῦ κήρυκος.
Murry apparently makes it the end of Klyt. speech.
The irony has a different tone if Klyt. is speaking.
Κῆρυξ A.Ag 613-14
τοιόσδ᾽ ὁ κόμπος τῆς ἀληθείας γέμων
οὐκ αἰσχρὸς ὡς γυναικὶ γενναίᾳ λακεῖν.
The manuscripts ascribed this to the herald, but modern commentators have suspected this and apperently everybody after Fraenkel ascribe it to Klytaimestra. Fraenkel has a long discussion of this and for some of the key points gives quotes in untranslated Latin (thanks a lot!). For dramatic reasons, he considers it impossible that the speaker could be the herald, and also there are grammatical considerations, he says for example that "the article in ὁ κόμπος has a fully deictic ... force: 'of such a sort is this my boast (as revealed in my previous words)'".
If this ascription to Klytaimestra is correct, I think the logical explanation for this error in the manuscripts would be that if the text didn't include indications to the effect of "exit Klytaimestra", a copyist would have found surpring the following words (αὕτη μὲν οὕτως εἶπε κτλ.), which are clearly not addressed to Klytaimestra, and therefore "corrected" the text accordingly.
C. S. Bartholomew wrote:What does the Χορός know at this point?
I don't know. It's difficult to get full picture, because it's like I had to read the text with a microscope to understand it word by word and sentence by sentence. I could read the whole text a couple of times in a modern language first to get a better idea, but I consider that cheating...

C. S. Bartholomew wrote:Is it possible to read either τοροῖσιν or
εὐπρεπῶς in a negative way?
Χορός A.Ag 615-616
αὕτη μὲν οὕτως εἶπε μανθάνοντί σοι
τοροῖσιν ἑρμηνεῦσιν εὐπρεπῶς λόγον.
My first instinct was to understand τοροῖσιν negatively, like 'stinging' i.e. bitter or the like, but neither LSJ nor any translation I read support this. I guess εὐπρεπῶς or εὐπρεπῆ (whichever reading we accept) has some irony in it. But these are, again, difficult lines.