If the Holy Father had particularly wanted to endorse Darwin's theory, he would have done so. The fact remains he did not.
I believe what the Pope was saying is that there is scientific "proof" (at least abundant evidence) for biological evolution even cosmic evolution for that matter.
But this is what we would expect in a divinely created Cosmos evolving in space and time according to the divine Logos of the Beginning, from Alpha to Omega.
Darwinism carries absolutely no brief for that idea, certainly. Rather, the very contrary is asserted: In a nutshell, Darwinian evolution is not purposeful; it is "random," "unguided," essentially "accidental" and "opportunistic"....
How could you expect the Holy Father to endorse such an idea?
Do you think God has no power over random processes? That HIS power stops at the casino door?
The Bible says that every dice roll (or casting of lots) is determined by God. Why would “random” genetic mutations be any different?
Professing themselves to be wise, they became fools, And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.
Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves: Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen. - Romans 1:21-25