Signor Biondi writes in his introduction: "Although neither the original score of 1738 nor the later version performed in Vienna in 1742 has survived...." The original Vivaldi opera apparently used the same or a similar libretto as Giacomelli's opera called 'La Merope', and thirteen of the recorded numbers are from that opera.
Of the rest, one is from Vivaldi's otherwise lost opera 'Semiramide' of 1732, one is by Haase, one by Broschi, and the remaining ten from already recorded operas by Vivaldi - 'Griselda', 'Catone', etc.
Biondi has stitched this pastiche together very skilfully, using the proper libretto of Vivaldi's lost original.
In other words, this is a pastiche, with little new in it by Vivaldi, except possibly the 'Semiramide' piece.
Having said that, I thought it was very enjoyable indeed, played with great excitement, and very well sung. I am very pleased to have bought it & will play it again.
So who labelled it as a Vivaldi Opera, RV 726. which I'm sorry to say it certainly is not?
I have other excellent recordings of Vivaldi operas by Biondi, who is evidently a scholar. In his notes on 'Oracolo' he makes no false claims for it. So, if not Biondi, then who is the guilty party? Well, who is left? Recently a recording of a work called 'Germanico' was labelled as being by Handel, which clearly it is not. Is this the new trend - a sort of band-wagon jumping? Yours is the choice.