I see the following problems with metals:
The increase on a critical hit is a percentage (if the comments in this topic are correct), this results in quality increase following an exponential function. Same as in RL this looks quite harmless at the beginning... but a little while later, as soon as the numbers have increased over a certain threshold, the function takes off.
Then the quality of the resulting product in smithing is averaged with the quality of anvil and hammer. This has for the problems of being able to cycle an item repeatedly (as is possible with cast->bloom->cast) will move its quality quickly toward that of anvil/hammer within a few rounds, when adding in the % increase from the critical hit chance it's (statistically) easy to end up with a way highter quality than these, rebuild them, repeat - and that having reached a high quality anvil+hammer one can endlessly stamp out quality metal items from no-quality metal.
My suggestion is to turn all quality modifiers that are not consumed in an item transmutation - at least all objects (like anvil/herbalist table/compost bin/loom/...) but
possibly (not really certain about that) also the items used (smiths hammer, axe, saws, treeplanter pots) - into softcaps (so these can't raise ingredient quality anymore) and all quality formulas (for crafting, but also for things soil/water/seed in the tree formula) that still use arithmetic means into using
geometric averages.
Sure, this would both cut down speed of progression (as a single high quality ingredient would increase the result less) and couple the maximum achievable qualities (eg. for trees as the herbalist table wouldn't boost the result anymore) tighter to the qualities of the resources that can be extracted from the world - but that would be a good thing as IMHO Haven works quite well until the moment it reaches the point where the exponential functions take off, then it starts to fall apart.