This thread inspired me to look at this sequence from the post-Ha preview again:
Namely, the whole matter of "just what is written beneath that whiteout?"
For the purposes of this exercise, I've assumed that something was typed out normally to start with, and the whiteout was added as an effect on top of it. Thus, the spacing between "&" and the name/descriptor of the four Reis should be the same as the spacing everywhere else in the caption cards' font. While not 100% uniform, it is pretty darn close.
Having accounted for this initial space, we can test for what that initial letter might be. For testing purposes, I prepared a set of letters taken from the caption cards; "J" and "X" are approximated since they are never used in the preview.
Whatever the initial letter is, most possibilities are ruled out right off the bat by virtue of the negative space on the left side, left exposed by the whiteout. Here, I've tested the most obvious options. T and J pass the test; X is ambiguous; the others fail.
An initial "T" is by far more common than "J" (this holds for both English and Japanese), and "X" is a nonstarter, so "T" is far and away the most likely of the three. What word(s) or name(s) starting with "T", referring to Rei clones, could possibly fit in that space?
...how about "Tentative"? And sure enough...!
(NOTE: First and last letters of "TENTATIVE" are transparent to show their ability to "clear" the whiteout.)
So there you have it! Mystery solved, I think.
EDIT: Added letter reference sheet and tests.