Why are you insisting that Alice can only have UTXOs that are known by chain analysis? Why can't Alice mine coins, use Lightning, or use Joinmarket to obtain a private UTXO?
So, let me get this clear: For Wasabi to offer privacy in a trustless manner, the user must have already gained privacy elsewhere. Therefore, there is no Sybil resistance for a user who only owns non-private coins.
This means Alice and Charlie were in the same round, proving the coordinator is not Sybil attacking.
I can't explain your line of reasoning. First, Charlie is de-anonymized. Then Alice is tricked into thinking that the coordinator is not malicious and joins the next round with coordinator's inputs, Charlie's already de-anonymized inputs and her inputs. That's a successful Sybil attack.