You have a copy of a marriage license? Sure, there's an entry on Hawaii's list, but why has no document been forthcoming? Both parties are dead, so there is no privacy issue relating to the release of such a document.
Common law marriage?
Since the divorce court judge referenced in his decree exact details of the marriage, he most likely saw a copy of the marriage license before granting the divorce. That would be standard operating procedure. It is pretty rare for people to go through the trouble and expense of a divorce if they were never really married.
As for me, I haven’t seen the marriage license for any president’s parents.
Hawaii is not a Common-law marriage state, it was outlawed there in 1920, and you don’t need a divorce to terminate an informal “marriage.”
I’m thinking “shotgun marriage” for appearances with a knocked up bride followed by a quickie divorce so that Ann could legally marry Lolo Soetoro.