This happens from 8u20 b10, might be related to the fix of RT-36500.
In RTL orientation, saved colors on ColorPicker palette is not RTL. Please compare the snapshot for b09 and b10. in b09, the save color starts from right side, but in b10, it comes to the left side. And the label "Custom colors" is also align to the left side.

The UE spec says in RTL orientation,
. label is right aligned
. saved colors start from right
https://wiki.openjdk.java.net/display/OpenJFX/Component+Orientation+User+Experience+Documentation#colorpicker