On Minecraft version 1.15.2 mod version 28.4
Pretty much what it says on the tin, every time I attempt the ritual of the forest with terraforged, it doesn't accept the ingredients. I tried it for both the token of joy and the token of fear. I believe it has something to do with the vanilla tree growing event being cancelled and replaced with the terraforged version.

It needs to be the specific sapling mentioned in the recipe. Why does Terraforged have separate oak saplings to begin with?

There's not really much I can do here. You can always use CraftTweaker's JSON Recipe editing system to change the Nature's Aura ritual of the forest recipes to use a different kind of sapling.

TerraForged does not have a seperate Oak Sapling, using a normal Minecraft Oak Sapling does not work.
OP suggested that the tree growing event has been altered:

I believe it has something to do with the vanilla tree growing event being cancelled and replaced with the terraforged version.

For reference, this issue has also been reported to TF: https://github.com/TerraForged/TerraForged/issues/157

Well, if the mod changes the event in a way that causes Nature's Aura's subscription to it not to be triggered, then there's nothing I can do on my end.

True, I should've searched the TF issue tracker before commenting here.
They have previously fixed the incompatibility on their end, so I think they'll be willing to do so again.