One of the problems with autofocus lenses, is that the focus mechanisms are loose. This enables the motors to drive the lenses.
Another problem is most autofocus cameras do not have the split prism circle either.
So bracket your focus zones like you would exposures. Stop down if you don’t need shallow depth of field etc.
Is the 50mm easier to focus? I would imagine it is.
You could always mount a pure manual lense.