As our friend mentioned in his development, the possibly original text of the Septuagint was influenced and added to by these translations of Aquila, Symmachus and Theodotion. Of the five links you have posted, three are translations from Lancelot, and two refer to Alfred Rahlfs text. Of the two links you have posted below, one links to a website that has that version, which was based, for the most part, on the text of church tradition and the text approved by the Fourth Holy Synod of the church, which was edited by the professor and academic Panagiotis Bratsiotis (which is in used by Orthodox Greek Church). The other link that refers you to a double column (text and translation) is this text by Panagiotis Bratsiotis and Lancelot's translation, in which, if you notice, they have put brackets where there is text that Lancelot does not use.
The point is that, there is a produced, of a semi-critical edition by Alfred Rahlfs, i.e. the one you have posted in your links above, and a large critical edition, in individual books, which provides the whole tradition of the manuscripts and the church fathers. The semi-critical edition of Alfred Rahfls is republished and revised edition by Robert Hanhart, and the large critical edition is published by the authority of the academy of sciences of Gottingen (in individual books), which do not contain the words: "θαυμαστός, σύμβουλος, θεός ισχυρός, εξουσιαστής, άρχων ειρήνης, πατήρ τού μέλλοντος αιώνος", which words, have, apparently, been added to some manuscripts, such as these are: Alexandrinus Codex, Venetus Codex, Purpureus Vindobonensis (from the manuscripts in large letters), as well as a revision of Lucian's text, as well as a few manuscripts in small letters (which, usually, fall into the later medieval period and beyond). So, it is better to use the most critical publications, and not pay attention to others, even if they are of the orthodox church. For these words, are in the Hebrew text, and most likely, were added to manuscripts of the Septuagint, such as those I mentioned above. The first text you posted, this is considered, propably, the Septuagint text.
Here is the text:
ὅτι παιδίον ἐγεννήθη ἡμῖν, υἱὸς καὶ ἐδόθη ἡμῖν, οὗ ἡ ἀρχὴ ἐγενήθη ἐπὶ τοῦ ὤμου αὐτοῦ, καὶ καλεῖται τὸ ὄνομα αὐτοῦ “Μεγάλης βουλῆς ἄγγελος”· ἐγὼ γὰρ ἄξω εἰρήνην ἐπὶ τοὺς ἄρχοντας, εἰρήνην καὶ ὑγίειαν αὐτῷ.
Transcription of the text:
óti pedhíon eghennéthe emín, iós ke edhóthe emín, u e arché eghenéthe epí tu ómu aftú, ke kaléte to ónoma aftú “Megháles bulés ággelos”; eghó ghar áxo erhénen epí tus árchodas, erhénen ke eghíean aftó.
And the translation is this:
For a child is born to us, a son is given to us, whose Supreme Authority is set upon his shoulder, and his name is called “the messenger of the Great will”; for I will bring peace upon the chiefs, (my) peace and (spiritual) health (will come) through him.
I hope I've got you covered. Good research!