The changes fixed in #1346 has uncovered two minor bugs I've been able to reproduce regarding the attunement. As mentioned in the comment of the closed issue, when a attune-qualified player walks into the altar, their position is de-synchronized relative to the other client's perspective. In addition, another odd phenomenon occurs when another player walks into the altar while the current attunement is ongoing - It will cause the attunement to reset, as well as resetting the player being attuned's position correctly in place. Very subtle issues, but nothing major in my opinion. Here are screenshots provided that show the perspectives of the two test clients I have running:

Perspective of an outsider:

Perspective of the attuned:

Provided below is a video reproducing the reset glitch. The audio is intentionally kept to further evidence the reset happening.

https://imgur.com/fO6TSR4

Do note that this is not reproducible if the player that walks in has maximized AS research. This only occurs to someone who has not started AS yet.

Hope I was able to be of help!

P.S: A lot of my friends are very excited to play this mod on our modpack! :) My favoritism with Applied Energistics 2 begins to wane...