Anima is almost certainly not going to exist in the same context it does in FF X. I'm thinking they chose to include it mostly because it matches the whole "doom and gloom" theme Endwalker has going on.

I'm also really curious about who this individual related to Fandaniel is. If they're not simply a post-humous character driving his motivations, they could potentially be a co-conspirator; possibly even a higher authority he's answering to.