I'm trying to implement a new disease which mutes the player and makes them unable to use shouts until cured.

I've created a new magic effect, DisDamageShoutRegen ("Crimson Plague Muteness"), with effect archetype Peak Value Modifier and Constant Effect, associated item ShoutRecoveryMult. Flagged as detrimental, recover, no duration and no area.

I then created a spell using this effect, DiseaseCrimsonPlague, type disease, constant effect on contact. DisDamageShoutRegen set to 50,000.

I then created a new wolf race - Plague Wolf - and added the spell to the wolf attack data.

I then loaded the game, got attacked by the Wolf and caught the disease when attacked. I can then shout one more time, before the shout cooldown timer is increased so I can now no longer shout.

All seems to work fine so far. I now need to provide a cure.

I then went back into the CK and created a new magic effect, DisCureShoutRegen ("Crimson Plague Muteness Recovery"), with peak value modifier, fire and forget on self, associated item ShoutRecoveryMult, flagged recover and no duration.

Added new potion, CureDiseaseCrimson, added effect Crimson Plague Muteness Recovery, set magnitude to 50,000.

I then realise that the shout cooldown timer has already been ticking - and although it was set to -50,000 on infection, it won't be that by the time the player is cured - so the +50,000 recovery potion will actually end up making the cooldown even faster than before infection.

I then try a different approach - remove the magnitude, and simply added keyword "Muteness" to the original DisDamageShoutRegen ("Crimson Plague Muteness") and added a dispel keyword "muteness" to DisCureShoutRegen ("Crimson Plague Muteness Recovery").

However, when I try it in game, get diseased and then try and cure myself with the potion, the disease description goes away so I think I'm cured, but the shout regen never recovers.

Am I missing anything simple here, or am I going about things the wrong way?

Is there an easier way of doing this - maybe using SKSE?

Sounds like the cooldown is only calculated once after the shout is cast. Try using a script with this function instead http://www.creationkit.com/SetVoiceRecoveryTime_-_Actor.