Thank you for posting your question on History Hub!
A search in the National Archives Catalog unfortunately did not render any results for the Castro/Boutillier family during that time period as California was under Spanish rule then and we do not have access to any of those records.
A search was conducted in the 1850 Census for the last names of Castro and Boutillier in California on Ancestry and those results can be found here for your review:
Please keep in mind that the 1850 Census was the first Census to include California and that Ancestry is a subscription-based database, but it is available for free public use at all National Archives facilities and many public libraries.
I would also recommend that you reach out to the California State Archives as they received a lot of the records that had been created under Spanish and Mexican rule. You can find a link to this archives below with their contact information:
We hope this information is helpful and best of luck with your research!