Hi, @roxburn!
Unfortunately, you can't currently set a user's password via the API. You can invite a user[1], or reset their password (they get a reset email and get to choose their new password), but you can't provide the password yourself.
Alternatively, depending on your ftrack license, you can also configure Single Sign-On via SAML[2]. This would allow you to entirely bypass the need to have your own custom user synchronization tools.
In the short term I can share your use case with our product team but the above are your current options.
Cheers,
Patrick
[1] https://ftrack-python-api.readthedocs.io/en/latest/example/invite_user.html
[2] https://help.ftrack.com/en/articles/1430063-single-sign-on-via-saml