ouch. I did not think it was possible to use adapters and have it wired wrong...
With 120 (30 amp) you have 120 on the HOT side and noting on the NEUTRAL side.
With 240 (50 amp) you have 120 on the HOT side and an opposite 120 on the NEUTRAL side; together they double the voltage.
This is why the plugs look different, so you do not plug a 120 device into a 240 outlet.
The adapters are meant to isolate the 120 opposite voltage so it is not used in a 120 application.
In a 50 amp camper you have an A and a B circuit, so almost like two separate electrical systems in the camper to allow you to power up multiple electrical hog devices. One circuit, A , is the 120 voltage, and the other, B, is the opposite voltage. So, from the circuit breaker all the voltage goes out as 120, never 240. I guess you could have a 240 outlet but that would be wired specially and have a special 240 plug like you house clothes drier.
If this is confusing, then think of it as water. With 120 you have a garden hose blowing 120 gallons per minute into an empty pipe so the water flows at 120 gpm. With 240 you have a hose blowing 120 into a pipe that has a vacuum sucking at 120gpm, so you are pushing and pulling at the same time. The analogy breaks down a little here, but imagine that together they make the water flow out at 240 gpm together- where with just the one it only flows at 120gpm.