Welding it isn't entirely impossible I suppose if you find some NASA welder guy, but I suggest you entirely forget it. It is a thin casting, and it will be impossible to avoid warping, these bearings need to be positionned very, very precisely. Plus it's a casting alloy and they often weld terribly anyway. Also, the casting deformed before cracking so yeah, everything already moved anyway.
So I'd say no hope in this direction.
There could be some hope if you happen to know some guy with an industrial lathe willing to help you make a new cover, but that is definitely some work and probably not cheap unless you're good friends. I suppose it is an unplausible solution though.
You need either a new cover or a new motor.
I was able to find a new cover for my motor here in China, but it was a QS motor which are relatively common/easy to source. No idea about your motor, can't say if it's common or not.
I suggest you check the classified for a bike like yours being sold for parts. You could get a second hand motor cheaply.
Or just ask your relative to buy you a brand new motor

The insurance might work.