We should be able to craft directly from our retainer inventory and not being able to is one of many of the little inconveniences about crafting. For example, LET ME SWAP CRAFTERS WHILE STILL IN THE CRAFTING WINDOW WITHOUT HAVING TO CLOSE IT SE.

But anyway, despite the fact that I'd love to be able to do that, SE already said that we are unable to craft from the retainer inventories due to technical reasons, I can't remember the specifics but bear with me here, it's something like the items in our retainers are stored on a separate space to our inventory and they can't have one connect to the other because it would cause too much stress on the hardware.