That's exactly what I thought when I saw the diagram. It's a design problem and the permanent fix would be as you say a baffle plate or move the breather to a position away from the main oil fling. A breather should never be in direct line with oil flow.
Talking about the modified breather ?

.
I was tuned in to the post cast last night and about half way through, we received a trick or treat visit from our grand kids ??.
I picked it back up latter, but it was not live at this point of course.
Forgive me if I am wrong here, but I was listening to the Scottish couple, who where talking about their MG4 going back for the oil leak, after only having the car for just less than one week.
The car has been at their local dealer for nearly three weeks now, I thought the lady said.
She said the dealer had dropped the oil level first and carried out some test drives, but it was still leaking !.
If I then heard correctly, she then said they had fitted a different breather !.
This really picked my ears up alright, as I was not aware that any of the modified breathers where available in the UK yet ?.
A little latter in that conversation, the lady owner reviled that her dealer had carried out a temporary
modification on the original breather.
By somehow increasing the high / length of the original factory breather assembly.
They had carried out further road tests and the car now appeared to be oil leak free and fine !.
But they where NOT allowed to released the car back to the owner, because they wanted to install the official replacement breather first, when it arrived.
This is understandable, because the car was not approved to carry this mod as yet.
But, nice to hear that this dealer WAS trying to help with finding a solution to the problem.
This was the point in the pod cast, when our door bell rang and therefore missed any further live comments on this subject - never mind !.
IF the combination of lowering the oil level and extending the height of the breather tube does indeed provide the long term fix, then do we conclude from this, that heavy oil sling from the box is main cause of the problem here.
Caused by overfilling of the cases in production would explain why some cars leak and some cars don't maybe.
So, a belt and braces approach is implement because.
( A ) Less volume of oil to be thrown in a upwards direction, reaching the breather in a mist form.
( B ) Increasing the overhaul height of the breather tube, prevents the oil sling / mist reaching the extra height achieved by extending the tube I wonder ??.
Do I get the impression that every breather pipe will be automatically be replaced though - NO !.
Oil level checked and corrective action taken at the point of the PDI - YES !.
Cars that are reported to MG dealer for leaks AFTER having had the correct oil level corrected.
These are the cars that are likely to receive the modified breather assemblies in my mind.
"Answers on a post card to ............

".