My concern about using treated lumber for raised beds involves lining the beds with plastic.
Plastic sours the soil.
It also breaks down and earthworms do not like it. People in wheelchairs need to be able to get up to the beds without leaning over. The best designs I have come across incorporate a window box design, trellising of plants, a bench that has railings allowing people to get out of their wheelchairs and work. Another is the use of livestock watering troughs. Holes punched in the bottom ensure good drainage and access for earthworms.