Can you ever get perfect alignment?

I use the Kuzma Airline (linear tracker). I don’t know that any third party protractors or other alignment tools (apart, perhaps from azimuth) would be useful- the arm comes with a simple gloss cardboard ’card’ with appropriate markings. I use a magnifying glass to get the points on the alignment card to the center of the stylus, as much as I am able to see that with modest magnification. There are two marks, like "null points" but given the straight line tracking, these don’t describe part of an arc, as with conventional pivoted arms.
The greatest difficulty is moving the very heavy arm pod (Kuzma XL) to get the arm into position. It can be time consuming, and even though the simple cardboard jig doesn’t seem particularly sophisticated, there is a big difference in result between "close enough" and "spot on" (or at least as "spot on" as I can make it, in light of the equipment involved).
The additional trick with this arm is that it is supposed to be level, but at a slightest cant inward toward the spindle-- "too level" may result in the stylus hanging up on a groove.
Although I used to view this process with trepidation, I have owned the arm a long time and am now pretty good at setting it up.
Adding a Minus K anti-vibration platform beneath the table/arm assembly required additional jiggering-- since the table has no real center of mass to balance the load, and requires a balance between the center of the table and heavy arm pod for the Minus K top platform to be level. (I use an HRS platform between the Minus K top and the turntable-- so it is a lot of physical work to get the table in place just to start the set up process).

avanti1960mthe reason I say we can’t get it perfect is because every form of alignment has only (2) points on the side of an album where the stylus is perfectly tangential to the grooves ...

If you can achieve tangency at those two null points, that's as "perfect" as you can get. But if you align the cartridge body rather than the stylus/cantilever assembly by using a mirrored gauge, it's likely that you haven't achieved tangency even at the null points.

I have always found the two points on the tonearm arc an interesting phenomena. In a dialed-in system kit, room, if one is in audiophile mode, you can hear when the stylus crosses these points. the focus gets dialed in. The records grooves are the smallest, and the revolutions faster as the tonearm/cartridge approaches the spindle. This makes it harder to track the inner grooves of a record. It therefore makes sense to set up the tonearm to try to ensure one of these points are closer to the spindle.

Another phenomena some are not aware of with the pivot tonearm. Look at the shape of the tonearm arc on your alignment tool. It is obvious that the tonearm/cart runs at different speeds. Faster up to midpoint - then slowing down after that.

Its impossible to set this up, so I am forced to talk the dreaded audio theory here, but, if there was a race with the linear tracker, and the pivot arm was set up on the outside, it would eventually end up overtaking the linear tracker, and the pivot arm would finish up on the inside.
So even if the turntable runs at a stable true 33.3, the tonearm does not.

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whart
The additional trick with this arm is that it is supposed to be level, but at a slightest cant inward toward the spindle-- "too level" may result in the stylus hanging up on a groove.

whart - I know a couple of owners that own the Kuzma Airline and the ET2. They confirm your findings. The ET2 has a very smooth bearing (slippery in comparison to the Kuzma). It needs to be level and will not get hung up. However if it is not level, it will affect the set up. The ET2 has a larger surface area, stationary manifold. The Kuzma's is smaller and moving. Two very different designs.