The Eldar are one of the oldest races still alive in the universe (Necrons do not count, they are souls trapped in unliving immortal shells). They have probably seen a million races come and go, so they probably don't keep up with the new species unless they have to.
Let's just call it the Souldreamer/Giant Eldar Robot (GER for short?)/Khel-Shadul-Anas (KSA?).
And ignore wichever geims worcsop property it is legally totally distinct from anyway.
This is eat-a-tau Verse, wich does not follow the WH40k 100%.
About the Eldar not knowing Kroott and TTau:
If that part works somewhat like the WH40k Kroot/Tau, then they are rather new on the Galactic Scene. So some old, seclusive living Eldar whose job is to handle Souldreamers might not have much contact with them. Or heard of them. You know, Souldreamers and Traveling do not mix that well.