Tempering could be fixed with a couple changes or one sweeping change.
Number 1 is that you can choose to keep previous rolls. This is exactly how the enchanter works.
Number 2 is that more manuals are added so nothing rolls more than 4 things on it.
Number 3 is that you choose any roll or smart roll on each attempt. Any roll can roll anything. Smart roll will not roll what you just rolled.
The sweeping idea is that enchant scrolls are removed from the game. Mythical Sparks now reset an item and can do so unlimited times but the cost goes from 1 spark to 2 and then 3 max.
Masterworking could be fixed with 1 change. That change is adding another system that removes the RNG on masterwork crits. You just pay more and choose. Yes its much more but you are not at mercy of RNG anymore. So if on average it takes say 60k obdulcite to hit a triple crit in currrent system then this additional system will cost you 60k obdulcite to upgrade your item to 12/12 and choose the crits. No mixing both system at same time. On each reset of item you can choose how to masterwork the item but have to stick with that method until reset again.