1. It commonly happens to me that I'm told I need e.g. "0.2 kg leather", but when I select from my inventory "2 leathers" that say they weigh "0.2kg" total, then I'm still told that I need e.g. 40g extra - because it was actually supposed to be 0.24kg while they were exactly 0.20kg.
It can also go the other way - I might be told that I have "0.2 kg" of something, but then when I use it on a recipe that says it needs "0.2kg", it turns out there's still 20g leftover, because the "0.2kg" I was shown in the inventory was actually 0.22kg.
I don't know if it's exclusive to kg base unit, caused by some calculations between Ibs and kg, or is there a similar problem with Ibs too - I've only been playing with kg. But it's pretty bizarre and very inconvenient, because I sometimes literally can't tell whether I have enough of a given material for a recipe or not, before I try to actually execute the recipe, and to do that, I first need to set up all the other conditions too. If I only want to check whether I can do it or not, I should be able to do that by comparing the two numbers that I'm given (how much I need and how much I have), and now it doesn't really work this way.
2. Sometimes when crafting or cooking there is a label "Ibs kg" shown instead of just "kg". Sometimes also Ibs weight is shown instead of kg during crafting, completely omitting the conversion. (Of course I'll gather concrete examples when I next notice them, and add them to this post, for now I just wanted to flag that this is a thing that I've been noticing.)