You were right, I had it listed as Uta/Hiori/Kirara with Kirara having the skill, should be Uta/Hiori/Yuki with Kirara having the skill.

I think you're confusing Kirara with Yuki. Yuki's talent is item drop rate up, Kirara's talent is bonus item from crafting. I mentioned that Yuki has lucky because in the section for lucky you mentioned Uta, Hiori, and Kirara as the ones having lucky. Unless it's a mistranslation which honestly it could be. I occasionally get extra items from crafting on ng+ despite no one having lucky.

Fraction HP Gain: Don't know, I hate the item crafting system so never used it :) Yes though I think if you got a buff duration up from say Support Rena it might last longer.

Lucky: I initially thought it just rolled the 10/20/30% once for each person with it per item (which would line up more with what I've seen in game), but the xml file for it specifically gives a cap of 100% so I'm not sure.

Yuki may have Lucky but she has a unique passive (shown on her Talent Page) that gives her bonus items from crafting - it should say like "Chance to get extra item from crafting (+ or ++)".

E/S is flat yes, I'll fix that.

You put an asterisk at the end of the effects for fraction hp gain but didn't explain what it was for.
When you say X% hp over time, do you mean you get that much hp each tick or total over the time of the buff (presumably total increased if the buff duration is increased)?
For lucky, you say that it stacks per person. Does that mean if I use 3 people to get luck 3, I'll have 90% chance (30% per person) of an extra item, essentially meaning lucky gives 30/60/90%? Doesn't seem to be true in practice. Or is that just denoting that it stacks up for each person with lucky going from 10 to 20 to 30? In that case, what does the 100% cap mean? You can't get more than double the items? Also, Yuki has lucky.
Ether recovery speed up's effect seems to be a flat amount rather than a percentage, based on the in game tooltip.

The ones listed in the "Character Abilities" section are special. They aren't the same type of bonus as the others, and will not show in the crafting preview.

The affixes under "Character Abilities" are applied to an item if:

1) The item allows it (e.g. you cannot grant "Death Strike" to a support item because it targets your own party instead of enemies, it has to go on an "Attack - One" or "Attack - All" item)
2) At least one of the members of the crafting team has unlocked the ability to apply that effect.

You can only these effects on the item from the menu, or when you use it (in battle, or again from the item menu). It will not appear in the crafting preview.

Example:

If I have the "Starting Lineup" (Ao, Kokoro, Rena, Yuki) craft the Tamagoyaki, it grants HP Gain XS (default) and the Attack Up S effect (from Ao and Yuki each giving Vitality Boost). This team will be able to grant "Flexibility 2" to any items they create (if applicable), because Rena is able to learn that.

Thanks, I have more question about Crafting Affixes under "Character Abilities" category

How are these abilities work? Does it only affect item that have the same slot name for them? ( I can't find any so far in chapter 5) or it is a passive add into the crafted item? For example, if I have character with 'Freshly Ground 1' craft Egg roll, will Egg roll has 'Recover 5-10% HP and 4-8 HP% over time' effect?

Lastly, what are the must-have crafting talents in your opinion?

Injure and Obstruct work differently. I didn't include them because they are't put onto items themselves, they enable affixes to be added.

They work as follows:

If an item has a slot for Injure, Obscure, or (less commonly) Damage, then depending on the crafting team, a trait may be granted into that slot.

Injure, Obscure, and Damage slots are given random ailments/damage. Generally, there are patterns (e.g. Flashbombs almost always get Blind in Injure slot) but not always (e.g. Slime Bomb), and it depends on the talents you've unlocked for your team as well.

In regards to this list, it would be like: Creating a Stun Gun with the "Building Connections" team gave me "DEF Down S" in the Obstruct Slot. What exactly does that debuff do?

As for your other question, multiple versions of the same ability on a crafting team can either strengthen the effects of traits that fall into that particular category (e.g. Def Down S -> Def Down M) or change it (Poison -> Paralysis).

Thanks. I can't guess what some of those effect from the name alone.

Does the 2 and 3 version (like Freshly Ground 2, Freshly Ground 3) can obtain from having two or more character with the same ability craft the item?)

BTW, I think you missed "Injured" and "Obstruct"