Hm.
First one is really odd. Just continue to the nearest (or even a nearby suitable airfield). Planes don't use alternators to stay in the air.
The second one, whilst anything is possible, is it likely that heavy rain stopped the engine? I can go with full immersion stopping an engine (obviously) but 'just' heavy rain? Perhaps something else caused the engine to stop?
Does this sound a bit odd: "retracted the flaps to try to improve the braking action on wet grass". Some presence of mind in the circumstances to make that analysis and decision...?