The server never takes custody of funds, not even for a second (unlike p2plnbot), but I hesitate to use the phrase "100% non-custodial" on what is essentially a 2-of-3 multisig.

From the buyer's perspective, the moment you hit "send" on your wallet you no longer have control over that money. It is now contractually locked in an htlc where the seller can take the money if the escrow gives him the preimage, or -- if the escrow does not give the seller the preimage -- the payment will time out within 2 weeks and the buyer will get his money back.

I'm not sure what to call that. It's not "100% non custodial" because you, the buyer, no longer control what happens to the money. It's also not "100% controlled by the seller" because he can't take the money without help from the escrow. It's also not custodied by the escrow at all, not even for a second, because all the server is doing is giving a preimage to the seller or withholding it.

The term Unchained Capital uses for their similar setup is "collaborative custody." That is the term that I think fits best.