The layout library now contains support for implementing right-to-left layout for right-to-left languages and can support mixed direction layouts. This support comes from two features:

Symmetry between adobe::layout_attributes_alignment_t::align_forward / adobe::layout_attributes_alignment_t::align_forward_fill and adobe::layout_attributes_alignment_t::align_reverse / adobe::layout_attributes_alignment_t::align_reverse_fill, especially with regards to guides.
The ability to construct a layout with items reversed using adobe::eve_t::add_view_element.

With these, implementing RTL support is fairly stright forward, if your content is in a RTL local, then add the items to the layout with the horizontal alignment attributes flipped and in reverse order.

Todo: (sparent) : At this point, no right-to-left languages are supported by the Begin example application. I believe the necessary support is now in the layout library, we'll be testing by implementing RTL language support in Begin soon.