is a copy of a typed agreement for money in exchange for interest in real property that is signed by both parties acceptable

That depends.  In many jurisdictions, contracts for the sale of an interest in real property require more formality than just signatures, for example witnesses or acknowledgements.  I don't know what the law is in California.  Also, you've indicated that there has already been some sort of court decision on the issue.  Without knowing the details, I can tell you that it is very difficult to reopen a case which has been decided.