I wondered about the artwork, though I don't think the actual fall of Troy was depicted was it? - just some scenes of parts of the story. My feeling is that the telescoping of time was just artistic licence on Virgil's part, in order to give an historic reason for the enmity between Rome and Carthage.
What did startle me on reading Book Four was that Dido came across as positively unhinged. "Hell hath no fury like a woman scorned" I know, but for someone who supposedly loved Aeneas, she is extraordinarily vengeful. As soon as Mercury tells Aeneas that he must go, he knows Dido will be enraged, rather than distressed:
"... What can he dare say now
to the queen in all her fury and win her over?" (349-350)
And then when he is asleep on his ship, he dreams that someone like Mercury warns him:
"... That woman spawns her plots,
mulling over some desperate outrage in her heart" (702-3)
It seems to me that Virgil is excusing Aeneas' treatment of Dido by portraying her as someone positively dangerous from whom he needs to get away. However, given that he was ordered to go by Jupiter, the only reason for her portrayal has to be to explain the enmity between Carthage and Rome.
It's a long way from the beautiful, grief-filled lament "When I am laid in earth" from Purcell's "Dido and Aeneas".