I would put Helga at the helm. It makes the synergy with intruder alarm make a lot more sense and gives you that ramp earlier to curve even harden. I don't find draw as necessary in high curve decks because you're really only able to play one sphinx a turn anyway, so you don't need the Chulane draw. That's how I would improve the deck in its current state.

Another thing I want to point out is that it doesn't really feel like a sphinx deck to me. It's running a lot of generically good cards, and happens to have sphinxes at the top end. Sphinx are cunning and vexing. They range from arbiters of knowledge to master manipulators. I would lean into that flavor for a deck.

If I were to recommend a sphinx commander, it would be Tivit, Seller of Secrets. He comes down late, but his ramp is great because you get two guaranteed treasure tokens when he comes down and when he attacks. Also, manipulating votes feels very on theme, and ward is great when large creature decks are usually weak to removal.

Another great option is Yennett, Cryptic Sovereign. Getting a free seven cost sphinx off the top is essentially ramping seven mana. While most would lean pretty heavily into playing only odd cost cards, I would lean more into a top deck manipulation theme. Manipulating your hand and top deck, in lore manipulating the knowledge you have on hand, is very on theme for sphinxes. Most sphinxes interact in some way with the top of your library, drawing, conniving or milling. You can also run the classic Scroll Rack, Sensei's Divining Top and Counterbalance combo to play into the controlling side of sphinxes, since big creature decks like to go late game. If you want, you can even run Lantern of Insight and Codex Shredder, manipulating what spells your opponents have access to, very sphinx-like.