It's not surprising that California courts would want to enforce (1) mediation agreements, (2) in family law cases. We like the former. We hate the latter. We want them resolved. So, so badly.
Which makes the outcome of this case not at all surprising. It's a mediation. A quasi-religious mediation, but a mediation nonetheless.
(For a sense of what the mediation was like, here's a snippet from the ultimate agreement the parties signed: "Clark and Anna met for four days to work towards reconciling their relationship. With God's help, and with the desire to honor and glorify God, Clark and Anna heard each other and addressed their failures. Although they are filing for divorce, they desire to live a life of peace as they continue to serve and parent their children. Please pray for them as they grow in their relationship with God, their children, and others." You don't usually see stuff like that when you mediate with JAMS.)
Did the parties dot all the i's and cross all the t's as you're usually required to do in most family law cases? No. They didn't. They did some financial discovery. But not everything that's traditionally required in the litigation setting.
But that doesn't matter. Notwithstanding some facially strict statutory requirements, the Court of Appeal holds that the mediation agreement is binding. What they did at the mediation was close enough.