Thanks for the info. You are right. The diagram doesn't show converter between house generator and house battery. The diagram below does show that converter.You have a lot of missing fuses or breakers in that diagram, I guess you know that.
You should use a breaker between the vehicle battery and the DC2DC charger rather than a fuse so you can maintaing the system more easily. In other words you can flip the breaker like a switch to allow you to work on the downstream side of it. I don't know what the purpose of the ISO relay is in your diagram. This is not required by some of the DC2DC chargers, although it might be required by some.
The DC to DC charger does not typically take output from a generator, but it could if your generator puts out 12V. Often generators put out 110V. In that case you will need to put a battery charger in between the generator and the coach battery.