I believe what you are saying is that, if Wrath is cast before Solar Eclipse ends but lands after it ends, it will benefit from that Solar Eclipse . . . which seems logical. However, what seems strange to me as a counterpoint is that I'm near 100% that a Wrath cast within a Solar Eclipse but landing outside of that Eclipse can proc a Lunar Eclipse.
i.e. Wrath Cast, Solar Eclipse Ends, Moonfire cast, Moonfire hits, Wrath hits, Lunar Eclipse starts
That would seem counter to travel time having no effect on Wrath's damage. I'll have to get on a target dummy to take a look at relative Wrath damage and if I am correct on my perception of the above on Wrath proc'ing Lunar Eclipse when cast withing Solar but landing after.
EDIT: Built a quick Youtube vid that shows my perception/recollection of how a Wrath that finishes inside Solar but hits after Solar acts in terms of proc'ing Lunar:
YouTube - Wrath Damage Calcs
However, the damage of that crit Wrath is so close to the Wraths that were completely cast and hit within Solar that I'd say damage is calculated when Wrath is cast but Eclipse procs are not determined until the spell hits. I don't say that off this sample of 1 -- I actually got 4 or 5 iterations of the same behavior -- this was just the one that most clearly showed Wrath finishing within Solar and hitting after. Even five is still a small sample size but, if the Wraths weren't benefitting, I think we could clearly see the 40% difference even in a small sample size.