As I understand it, you're looking for something like HorizontalLayout, but instead of starting from the left side, you would like to start from the right? There's nothing like that built into Feathers, but you could create a custom layout. Or you could use no layout and manually position the children in the ScrollContainer.
Feathers Help: Introduction to custom layouts for Feathers containers includes source code for a simplified version of VerticalLayout. You might be able to use that code as inspiration for a custom layout that is similar to HorizontalLayout.