Its not difficult to fix the actual keyroll. The real problem is most of the top coders feel its a waste of time and effort as the Emm's can be adapted faster than the code can be fixed. The ATMega & FunAU use a very inflexible method of recognising keyrolls due to the limited resources of these chips and thats the heart of the matter !
No doubt someone will fix it but its survivability in the long term is very limited.