Registrars are not delegated powers to change a final order unless both parties agree to the change ... that remains even under the new regime. I expect the mediation was to try to get some agreement between the two parties & move forward from there. So now that nothing has come out of mediation, it will be interesting to see what the registrar suggests as a next step.
If the problem of keeping the kid home from school on a pickup Friday persists (bearing in mind you have only had the order since late September, so early days) All you can do is keep a record of the times this has happens with a view to filing a contravention. If you do that within 12 months of the order being handed down, you won';t need to attend mediation to file.