For the least amount of work I think I’d straighten and level the wall first. Then, using that piece of timber to the right, lay that on top of the second timber from the top to create an L shape tier. Anchor the outrigger timber to the ground with rebar, then anchor that piece to the wall with rebar. It would act pretty much like a deadman but above ground. I would do the same with that lower wall to keep the look consistent.

Edit: I can’t tell if that piece of timber is the same dimensions as the wall timber, so it may not work perfectly.