Test that the barrel adjuster is OK by putting the FD into the middle position, and turning the adjuster. As you turn the barrel out, the FD should move outward. If it doesn't respond, the adjuster isn't working. Possibly it's so hard to turn for a reason, and you need to figure out why, or just go ignore it and add an inline adjuster.
As for the thumb shifter. It might just be a characteristic of the lever, or there might be extra friction in the cables. When you take the cable off to work on the adjuster, test the thumb shifter applying light tension on the cable with your hand. If it's still hard, then it's just the way it is and is another thing to live with.
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