There aren’t many entry points in the drivers foot well. Shouldn’t be anything coming through the steering rack or pedal box, since they go to the engine bay. The windscreen is bonded in and don’t normally leak, but worth a quick check.
My guess would be the bulkhead around the bonnet catch. The drain from the scuttle is in that corner, water runs behind the wing and exits behind the front wheel.
Unscented? That’s the boring way to do it!
Have you got your hand in under and right of the pollen filter housing? It gets full of decaying vegetation. And blocks brainage holes. I’ve just had my arm in side mine. ( cuts your hands up as there’s very little room. )aaaaaaaaaaaaaaaaaaaaand we still have a leak, the butyl rubber around the door inner panel fix appears to have worked so no leaks that way, the passenger foot well is dry only the drivers side seems to be leaking from the scuttle down into it. So although I sealed that electrical connector box thingy, its the only place water can be getting in.
So I have obtained some talcum powder (unscented !) and will try that approach ..................failing that its into a field with a can of petrol.