And the first link explain that shooting a child for stealing an apple from on orchard would not be self-defense.
So you agree now that according to German law self defense should be proportionate. That's the sentence you tried to refute in your message.
shooting a home invader mid burglary should be illegal
Because you don't kill someone to save a TV. It's basic human decency.
is illegal under German self defense laws
That's not something I ever said. I don't know. I presume it depends on the details, sometimes it's legal, sometimes it's not. I know it's the case in France.