Is is OK for you to stack the data?
Then you can use "order by" via a manually calculated column:
dt = Open( "$SAMPLE_DATA/Semiconductor Capability.jmp" );
dtstacked = dt << Stack(
columns( Column Group( "Processes" ) ));
dtstacked << New Column( "median",
Formula( Col Quantile( :Processes, 0.5, :Label ) ),
) ;
dtstacked<< Graph Builder(
Variables( X( :Processes ), Y( :Label, Order By( :median ) ) ),
Elements( Box Plot( X, Y, Legend( 13 ) ) ),
Local Data Filter(
Add Filter(
columns( :Label ),
Where( :Label == {"A1", "A2N", "A2P", "A2P1", "B1", "B10", "CAP"} )
)
)
);