IMHO almost every phrase must be changed. many sentences just seem, as if they were translated by a machine. that's the reason i don't really believe in you claiming that the translation is by a native speaker. if it is so, then tell the native speaker, he should translate the whole messages more freely, as no german will ever understand what f.e. is meant bei a "hauptrechner". (in fact it isn't even right, if you tranlate it back it is something like a "main computer" and not a host.)