Minfilia and the Echo

[Enkidoh]

I think it's likely an oversight because:

Spoiler:

Minfilia is a character Yosh-p created after he took over FFXIV whereas Ascilia was created by Tanaka's team. It is only in ARR that it is revealed that these character's are one in the same and this was likely only done as an afterthought. It's likely that Ascilia was never originally intended to be Minfilia.

A good plot hole for the lore team to fill though with future quests.

That's actually not correct - Minfilia and the Path of the Twelve were always part of 1.0's storyline right from launch. Also, the current lore team are the same as those who worked on 1.0, all they've done is clarify details in ARR that the original storyline was always planned to lead up to but never ultimately did. As for Ascilia-Minfilia, it's anyone's guess whether they had always planned that to be a big revelation or simply retconned it, but I'm likely to believe it's the former (it also fits in with the revelation Ferne gave ages ago that the first part of 1.0's storyline was actually mostly set within the Echo and the player didn't even realize it). But I digress..

Anyway, Alenore is correct - Minfilia's potency in the Echo isn't as strong as the player's, in that she can only view past memories of other people and cannot understand unknown languages, where as the player has both (an opposite to this was shown also in 1.0 where at least one member of the Path of the Twelve stated he couldn't view other's memories but could understand unknown languages, such as those of the beastmen), which he had made into a profitable venture.) The Echo seems to be rather inconsistent with it's potency in some people.

Also as to when Minfilia received the Echo, it's unclear, but it appears she may have received it during, or immediately after, the Battle of Silvertear Skies in the year 1562 of the 6th Astral Era (when the Agrius crashed into Silvertear Lake and the Primals were freed. Certain members of the Path in 1.0 actually mentioned that event was believed to have been when the Echo first sounded (what they referred to as 'the Fall of the Keeper', and that even Minfilia believed that theory at first, but then she started having second thoughts. Of course it doesn't confirm or deny that's also when she received the power of the Echo, but it's a good a time as any as it does make sense.