??:“We would like your cooperation, Professor Fuyutsuki.”
Mbryo: The Human Instrumentality Committee and Seele are basically one and the same, the former merely being the 'official' designation that Seele uses for more public activities. The fact that they appeared before Fuyutsuki as Seele implies that they are here for more ominous purposes.
Dr. Nick: Oddly, the Seele members other than Kiel use goofy voice changers in this scene, even though Fuyutsuki knows the identities of 40% of the monoliths thanks to being present at the Human Instrumentality Committee meetings. The monoliths speak with unscrambled voices later in episode 23 and in EoE.
And since we're talking about Seele, I personally feel like this is the place where the show's sometimes frustrating lore vagueness actually works the best. Seele is a thinly-sketched group of antagonists, basically just "the cabal" with "the evil plan" and some cool, ominous visual signifiers. It's a simple canned trope, but it's also a future-proofed trope since the group is too featureless to be seen as an expy for any specific real-world thing. This also helps to keep the show clear from any harmful real-world conspiracy theories, although the early fandom kind of went there with the wild (and completely unsupported) "Kiel is the Wandering Jew" theory.
Additional Commentary
Dr. Nick: Of course, this vagueness of the antagonists is an example of accidental greatness, as it resulted from a rewrite forced by an external event - the Aum Shinrikyo cult's deadly nerve gas attack in March 1995, a little over half a year prior to the airing of the first episode. It's always been a matter of fandom conjencture what was changed and how much these changes rocked the show's production process, and in the case of the western fandom we can be pretty certain that there are all kinds of juicy Japanese sources that have never been translated into English, but we do know that distancing Evangelion's plot from Aum's real-world atrocities was a major imperative for Gainax. One tantalizing, although a second-hand source is Krystian Woznicki's interview with the Japanese cultural critic Hiroki Azuma, who had talked with Anno about the rewrite situation among other things. Interestingly, the shape-shifting nature of the Angels too stems from this same impulse to make the enemy vague and abstract:
"The angels change their form for example into pyramids, into shadows. I asked Anno about such abstract characteristics of the angels. He said that this reflects the feelings of his generation. For his generation the enemy is not political. It is also not definite. I mentioned to Anno that such abstract characteristics of the enemy are very close to the conception of Aum as enemy (e.g. poison gas) which he admitted."
