The reason the R4 doesn't work in ACWW is that the R4 hooks a known function on the ARM7, which is the same in all games. However, ACWW does it's own thing on the ARM7, meaning that the hook no longer works and must be relocated. The R4 team never bothered fixing it, and why would they care?
It is possible. But it depends on what they did to the AR engine when they cannibalised it.