Howdy folks, Saman here to produce his two cents on the matter.
I'll start by saying I should return soon, unfortunately life has been stingy with free time to dedicate to the wiki for me, but I'm definitely working on Ingrid, before Alex even, whom, unfortunately, will have to wait a little more (I have to still handle Fatal Fury).
SPOILER SHIELD FROM NOW ON because I'm to lazy to obscure the whole paragraph.
Personally, from what we've seen of Ingrid, including World Tour, quotes, arcade etc.., my personal take would be to split her tier in physicals and hax.
The latter, would be easily Low 2-C, she destroys the parallel SF6 universe so casually and mentions several times her ability to consign universes to oblivion.
Regarding her physicals, I would upscale her to SF6 Ryu and, since her Alpha 3 MAX appearance is canon, to Evil Ryu and Psycho Drive Bison as well. She never confronts top dogs like Akuma directly, but she treats everyone with such sufficience, that it's indeed believable for her to be above every mortal.
I would also add a "possibly" to upscale her to the Darkstalkers, as Fighting Jam was canon to her, and she states to have stomped everyone, from Pyron to Morrigan, but those would be the crossover versions of the characters, not the main ones, so it's debatable whether or not they could scale equally.
That said, while she is repeteadly stated to be a higher-dimensional being, that alone does not suffice to bestow a tier anymore (iirc) and I don't believe there is a true R>F here (that's the appropriate term, right?).
Because, while the universes are portrayed as books to her, she never refers to them as fictional, as they're pretty much real to her and she is quite invested in their safekeeping.
I believe the books are a way to portray the universes, whether metaphysical or not, but they would be more akin to portals or higher-dimensional devices, like other fictions do with orbs, bubbles, paintings or other things.