I just spent a half-hour unraveling this only to realize it was a) totally irrelevant as a "bug", b) too long to post the full stupid saga. But I'll share the answer, because it's funny to me.
Basically, the Courier Prime font on Stimuwrite does a weird-looking apostrophe if the apostrophe happens to fall in a certain part close to the center of the page.
Spot the haunted column.
It's mechanically the same symbol in any other program, so it's not an issue at all. It's just so weird.
