Preface and reasoning behind my answer
There were several cases where Card fairly openly indicated that any discrepancies between the different Enderverse books are meant to be resolved by taking the later books as "more correct". This involves planned changes to the next revision of Ender's Game to match the sequels.
I have factored out full proof of this (including the "later works supercede earlier works as far as correctness" concept) into a separate answer:
What is Orson Scott Card's position on discrepancies between various Enderverse books?
To quote from that post, Afterword to "Ender in Exile" explicitly says later books' version of events trumps earlier books', especially original version of Ender's Game:
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. ...
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.
Why should I be stuck now with decisions carelessly made twenty-four years ago? What I've written since is right; those contradictory but unimportant details in the original novel are wrong.
Further confirmation specific to First Invasion came from someone discussing this with First Invasion books' author Aaron Johnston:
In terms of the first one, I was able to talk with Johnston about it, and he confirmed my suspicion that he and Card are continuing in the "fluid continuity" and "the stories must be good, and continuity will be altered to fit those good stories" approach that marked "Ender in Exile" and "Shadow of the Giant." So they are aware of these issues, but feel that the story they're telling now doesn't contradict the important moral and emotional aspects of Ender's Game, and so they're going with that, with hopes to alter future editions of Ender's Game.
As such, looks like the original Ender's Game story about Eros being involved in the First Invasion is wrong and presumably will be fixed in the next revision, because it contradicts the later story of First Invasion books which never mention Eros at all.
Eros was used by Buggers in the Second invasion.