Some companions have a crit modifier for crew skills, what's that mean.

It gives the item in question a better than average stat or such. At least it did a couple betas ago. Not 100% now that the builds have changed some.

I think it can also mean that the companion created multiples of the item instead of just one.

Yep. It basically means that you have X% chance to have a higher quality item than normal from that particular crew skill. If it's from one of the mission skills, I believe it means you have X% chance to get extra loot when your companion returns.

Some companions have a crit modifier for crew skills, what's that mean.

 

means if you craft blue or green quality item it has a better chance to be crafted as an "exceptional" item that item will have a random enhancement slot, pretty much if you put an enhancement in this will make that gear equivalent ( by base stats) to a gear that is 1 tire above for example

if you get upgradeable green after upgrading it will become equivalent of blue quality, upgradeable blue will become equivalent to purple of the same lvl and so on.

 

Do not confuse with orange gear, the blue gear will not have its damage or armor stat upgraded upon putting in enhancements if there is a slot all that will happen is a raw stat boost.

Crit result verries by skill.

A gathering crit means you got more items from the mission.

A Biochem Crit means you made more items (IE: 2 Medkits instead of 1)

For the skills like Armstech and Armortech, as stated previously it will give a boost to the item created.