Stop trying to figure everything out by asking endless questions on the message board and TALK TO A LOCAL PROBATE ATTORNEY about how to proceed from here.
Why are you concerned about being humiliated--it is your sister who should be embarrassed about not being more cooperative! The only way you all are going to get any information out of her is: one of you should file at the courthouse to become administrator/executor of the estate, which would then give you the authority to begin claiming all assets, and you could ask the judge to have your sister provide all financial information she has.
Executors fee in California is: 4% of the first $15,000 value of the estate, plus 3% of the next $85,000, plus 2% of the next $900,000. This estate is obviously worth more than $10,000 since you mentioned the existence of the CDs--undoubtedly he has other assets besides these. If you serve as executor, you get the fee; if you hire an attorney to be executor, they get the fee.
DANDY DON