OK, descobri (e enquanto respondi a pergunta original - atualizarei agora)
Foi um dos "não pensei no livro original", disse Card, no capítulo 15, que ele discutiu no pós-fim de Ender in Exile (citação abaixo).
Em Ender in Exile , o Card explicitamente elaborou em Abra:
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Abra não nasceu na Terra. Ele estava na colônia quando Ender chegou e, portanto, não poderia ter sido 3 quando foi fundada.
In all eleven years of Abra's life, only one thing had ever happened that mattered: the arrival of Ender Wiggin.
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No posfácio de "Exile", Card admitiu explicitamente que "os detalhes e a linha do tempo não estão exatamente certos" no Capítulo 15 do Jogo de Ender, especialmente no que se refere à existência de 40 anos da colônia antes da chegada de Ender:
Except for one tiny problem. When I wrote the novel Ender's Game back in 1984, my focus in the last chapter, chapter 15, was entirely on setting up Speaker for the Dead. I had no notion of any sequel between those two books. So I was rather careless and cavalier with my account of Ender's time on the first colony. I was so careless I completely forgot that on all but the last formic planet, there would have been human pilots and crew left alive. Where would they go? Of course they would begin colonizing the formic worlds. And those who sent them would have at least allowed for that possibility, sending people trained to do whatever jobs they anticipated would be necessary.
So while the meat of chapter 15 of Ender's Game is exactly right, the details and timeline are not. They aren't what they should have been then, and they certainly aren't what they need to be now. Since writing that chapter, I have written stories like "Investment Counselor" (in First Meetings), where Ender meets Jane (a major character in Speaker) when he is legally coming of age on a planet called Sorelledolce; but this contradicted the timeline stated in Ender's Game. All in all, I realized, it was chapter 15 that was wrong, not the later stories, which took more details into account and developed the story in a superior way.