Artifact Signing Public Trust in Japan: eligibility and documents for unincorporated associations and sole proprietors

I am evaluating Azure Artifact Signing Public Trust for an open-source Windows application developed in Japan, before purchasing a subscription or submitting identity validation.

The quickstart lists Japan among supported countries for organizations, limits Individual Developer validation to the US and Canada, and describes Organization or DBA validation:

https://learn.microsoft.com/en-us/azure/artifact-signing/quickstart#create-an-identity-validation-request

Could the Artifact Signing team clarify:

1. Can a Japanese unincorporated voluntary association (nin-i dantai), without corporate legal personality or a corporate registration number, qualify for Organization/Public Trust validation? Or is an incorporated entity required?
2. Separately, can a Japanese sole proprietor with a registered/notified business and a trade name qualify through Organization/DBA validation, despite the Individual Developer country restriction?
3. For each eligible category, which Japanese documents and Business Identifier are accepted? For example, are association bylaws and representative/address evidence, or a sole proprietor business commencement notification and tax records, sufficient? Are a D-U-N-S number or minimum operating/tax history required? These are questions about possible documents, not a claim that any have been submitted.
4. What establishes the right to use a trade/association name in the certificate CN/O, and are an owned domain and two same-domain email addresses required?

Please distinguish current product eligibility from general certificate standards and identify the applicable documentation or validation-team process. We want to provide accurate information and confirm eligibility before incurring charges. No identity-validation request has been submitted.