My Name is Hideaki Hagiwara in Japan.
Org(AD_Org_ID) of Workflow Process is setting from Default(login) Organization.
I think that we should take organization from m_po in MWFProcess
And MWFEventAudit has same problem at MWFActivity.
I'm sorry for my poor English.
Thank you for reading.
In the tests it seems the organization doesn't add any value, if logged in with * those records are added with *.
So, the suggested patch is harmless and I think it can add some value to know where is the org originating the workflow.
Added pull request https://github.com/idempiere/idempiere/pull/195