Possible issues:

• bloomery and pit kiln time could switch fairly easily. Use random tick / ITickable to determine when it's complete.
• How to handle fire pit? (i.e. it's tick based, so what does it do to the contents?)
• How to handle item heat? (probably just keep using total time, although that will be somewhat inconsistent, but probably for the best)
• With normal sleeping rules in a server, this works fine, although using fast sleep mods, this could result in other players "nuking"

Bunsan said in discord he would experiment with the possibility of moving everything (including time ticking) to player time.

Another thing to consider: how to "fast-forward" devices, i.e. the charcoal pit, when sleeping? Ticking is likely way to intensive, and likely won't work if using player time. Also opens a huge pit of inconsistencies and problems.