Can you not adjust your fletching jig for left offset?
RW or LW... it doesn't matter, as long as you don't mix them on the same shaft. LW should be offset to the left, RW to the right. Don't fletch them the other way! RW offset makes the shaft spin clockwise in flight, LW counterclockwise.
RW feathers are NOT for RH shooters, or LW for LH shooters. Funny thing... most archers in N. America want RW feathers, and most in the UK want LW feathers. Go figure.
So, your LW feathers are fine, and you can use them no problem. Set your fletching jig for left offset, and away you go. If your fletching jig does not allow offset, get a new one. Fletching your arrows with straight fletchings is not good... the arrow will fly much better with some spin. Think of it like a pitcher throwing a knuckle ball (no spin)... the ball fies very eratic... as opposed to a football, which flies true with spin.
Fletch your arrows LW, left offset, and you're good to go.