I think it will always be on loading that turning around will need to happen. I don't know of any front-loading bus in the US that allows wheelchairs or ECVs (even empty) to be tied down facing backwards.
A tip for those using ECVs is that if you are the only person who needs the wheelchair/
ECV space, you can always ask to have the seats on both sides lifted temporarily to give you a wider turning radius. It does also mean that the smaller ECVs are probably going to be the easiest when using buses (I know they were before, but it may be even more true now). The good news is that it's easier to get off the bus in general now. It should especially be much easier in cases where a bus has multiple stops and other guests remaining on when the ECV or wheelchair user needs to get off the bus.
It's unfortunately that they couldn't find a way to put more than two tie-down spots on the articulated buses. I know most cities don't, but, since WDW does have a much higher percentage of bus users with mobility aids than most cities, it would have been nice.