Well, the only reason she knew the location of the butterfly eggs was because she was reincarnated. I also get your point, but still, in the end they used it as a plot excuse for the FL to know certain things that she shouldn't, they didn't even bother to explain how she died and was reincarnated in the end (which I honestly appreciate, it's getting repetitive lately (?))
Furthermore, without the excuse of reincarnation, there would be no way to explain what Roxana's interest in Cassius is. We currently know that it is because his death is what will cause the downfall of the Agriche family. But without that information, the ML's well-being would have no relevance to her.