Thanks for the helpful background.
So the short answer is "no". The "Date Time Original" metadata tag is read-only for the SDK.
Investigating the use of IPTC Date Created a little more:
- The standard behavior is for newly-imported videos to have neither a "Date Time Original" nor a (IPTC) "Date Created". The "Capture Date" and the <sort date> at this point is the "Date Time Digitized". (Using <sort date> to refer to the observed sorting behavior of the video, which may not correspond to any viewable metadata field.)
- If, at this point, "Date Created" is set (either manually or via the SDK), this updates the "Capture Date", though it has no effect on <sort date>.
- At some point, I can do a "Edit Capture Time" with a shift of 0 hours. This has the effect of copying the "Capture Date" (I think) into the "Date Time Original" field. It also updates <sort date>.
- Once the video has a "Date Time Original", subsequent changes to "Date Created" are ignored by "Capture Date" and <sort date>.
There are some useful tools here for special-purpose use cases, but nothing good enough for a general-purpose workaround.