Wilhelm Johnen's book - true or fake?

[Graham Boak]

I suspect translation defects rather than fake, although perhaps you are right to be careful.

re formation, although the bombers were not actually in formation, they were close to each other in a bomber stream and it is not unheard of for one bomber's gunners to see a nightfighter attacking another. It rather depends upon the darkness of the night.

Ahead and on the level doesn't have to mean directly ahead or identical altitudes. I take it as a loose description. People look for stars using binoculars, why not bomber exhausts? Perhaps having seen a faint light, he was attempting to magnify it and see if it had partners? Not common though, I'd have thought.