Scale of Scientific Sins: All of them. Absolutely all of them.
Automation: Of just about everything, as exemplified by the sheer number of cornucopia machines, AI managers and scurrying utility spiders. Unlike most of the people who got this one very badly wrong, however, in this Galaxy, almost no-one is stupid or malicious enough to make the automation sophont or volitional.
GE and Transhumanism: Transsophontism Is Compulsory; those who fall behind, get left behind. Or so say all we – carefully engineered – impossibly beautiful genius-level nanocyborg demigods. (Needless to say, Cybernetics Do Not Eat Your Soul.)
Immortality: Possibly cheating, since the basic immortality of the eldrae and galari is innate – well, now it is, anyway – rather than engineered. Probably played straight with their idealistic crusade to bring the benefits of Avoiding That Stupid Habit You Have Of Dying to the rest of the Galaxy, though.
Creating Life: Digital sapience, neogens (creatures genetically engineered from scratch, rather than modified from an original), and heck, even arguably uplifts, too.
Cheating Death: The routine use of vector stacks and reinstantiation is exactly this. Previously, cryostasis, and the entire vaults full of generations of frozen people awaiting reinstantiation such that death would bloody well be not proud. And no, people don’t Come Back Wrong; they come back pretty much exactly the same way they left.
Usurping God: This one is a little debatable, inasmuch as the Eldraeverse does not include supernatural deities in the first place. On the other hand, if building your own complete pantheon of machine gods out of a seed AI and your own collective consciousness doesn’t count towards this, what the heck does?