For left handed writing switching to the uni-ball jetstream (RT SXN-210 or Sport SXN-150S) was a noticeable improvement for me. I do not know how they compare to the ones recommended for left-handed writers on the site.
why would pens perform different for right vs left? they're asymmetrical
The whole language is against you. Writing with your left means you can smear everything unless you do some odd maneuvering with your wrist.
In left to right languages lefties are draging their hand across what they just wrote and so need something that dries fast or it smudges. I suppose right handed hebrew writers would have the same issue (are their other bidirectional languages? )
Arabic, Persian.
Mostly because of smearing and the direction of writing: left-hand writers "push" the pen more, while right-hand writers are "pulling" the pen more (not totally and not 100%)