If you're stuck in coarse pitch you just need to fly faster to get decent rpm.
Once you get to operational altitude (>15000') then you'll find that it's no problem to get full revs in coarse pitch because the air density is lower, the engine is putting out more power anyway (closer to FTH ~ 16000') and your TAS is higher.
So really this only matters if you want to get into slow turning fights on the deck. In which case you're going to get yourself killed pretty rapidly anyway
. Actually it's probably quite a good learning tool because staying fast (say >200 mph IAS in 1940) is a very useful
life skill.
Since there obviously won't be a fix until the next patch, and we don't yet know when that will be, don't forget that CEM isn't really that hard in a single seat fighter if you turn off overheating, especially if you don't have to fly for range; you just leave the mixture in rich, control rpm with the prop control and boost with the throttle.
Trying, crashing, burning and learning is probably preferable to being grounded until the fix.
When you want more power, first increase rpm/go to fine pitch and then open the throttle.
If you've got a 2 position prop then remember your rpm limit, and don't change up if you're less than say 300 rpm below it (i.e. don't go into fine pitch in a Spitfire if you're getting more than about 2700 rpm in coarse pitch).
When you want less power, close the throttle first and then reduce rpm/go to coarse pitch.
[Actually it's not even that hard with overheating on because if in doubt you just open the radiator and accept the (relatively small) drag penalty.]