It's probably worth noting that for much of the "modern" era the aristocracy largely put their kids in the hands of nurses, governesses, tutors, etc. Which may explain a lot.

That said...

First, yes: Anevak reads as decidedly the elder to me.

Second: every new detail we learn about Tarvek's family and home environment is less reassuring than the last. One thing worth considering if if Mama Sturmvoraus might not have "needed killing," much as Aaronev did...and why.

If nothing else there's every sign Tarvek really did love the original Anevka...and at least some suggestion that the original was pretty scary in her own right, if mecha-Anevka is any reflection of the original at all. If she and Von Pinn were the best Tarvek was ever offered, that's a sad backstory. Live on Castle Wulfenbach, the society of the School kids, and friendship with Gil must have seemed like heaven in comparison--and being tossed out would be a truly Satanic "fall."

One of the reasons I keep hoping against hope they give Tarvek a reasonably happy future is that they've given him such a brutally UNhappy past, and a pretty ragged present. I'd love to see him make it to safe harbor.

One wonders if the reason Tarvek's entirely unshocked by Mama's death is because at the time he saw Anevka as the "protecting angel," acting to save herself (and by extension Tarvek) from someone even worse than Aaronev.