The fact that the original babies were murdered decades ago doesn't really change the moral calculus.

The Mengele question is a good one. I've not studied that very much so I cannot provide a very informed opinion on it, specifically.

On a deeper level, people justify any number of moral atrocities by arguing how they have led to beneficial advancements in this or that thing. Doesn't negate the evil.

It also assumes that similar or better advancements could not have been made in morally upright ways.

On the subject of honoring Mengele's victims, that seems to me a strange and almost perverse means of easing the conscience (which is not me making a moral judgment about you, to to be clear. Only responding to your comment about the general perspective).