I have x amount of savings of Yuan. I keep 6 month expenses in Yuan and the rest in Bitcoin.

When I need to make an unapproved transaction (donating to a Muslim charity if you are a Yighur for example). I go through the hassle of using Bitcoin, either directly or after changing to USD by P2P exchange.

Can you be more concrete? Here's what I'm imagining you're saying: first you take a month's paycheck out of the bank in yuan, in cash; then you walk down the street to a jeweler's shop that will exchange your yuan in cash for US$100 bills; then you send a WeChat message to a guy who sells Bitcoin, and the next day you take a taxi with your US$100 bills to a cafe, where he transfers you the Bitcoin and you give him the US$100 bills. Is that what you mean?

I'm wondering if somebody who spends all of their highly-controlled digital yuan in cash every month, and not on anything detectable, will draw suspicion.

This doesn't explain anything.

Who's buying yuan from you in exchange for Bitcoin?

Who's selling you yuan in exchange for Bitcoin?

Given that yuan is tightly controlled... How is Bitcoin hiding anything in this process?