One I want to add is: to be able to unlock a comment if you want to. I just finished my first buddy read and editions were pretty similar. But mine was at 42% for example and the other one at 45%. I needed to edit my own progress first to see those comments or I had to wait and read them later.

This is probably something I'll explore for the next wave of work on buddy reads!

I've just run into this on a buddy read with three friends. We're spoiling each other all over! We can manually add a heads up in the comment for which chapter we're discussing, but we didn't know we'd have to until well into the book.
I'd love to see a field between the progress and comment boxes where you can add a free response indicator (e.g. Chapter 7; Prologue) that will appear above the 'Reveal Comment' button when the percentage is unlocked.

I was precisely looking if anyone had brought this up, so commenting to add a voice to this suggestion!
I recently did a buddy read for a classic where the discrepancy in front and end matter (Introduction and endnotes, mostly) meant that we ended up with a gap of at least 10% between me and another reader. For instance, we both left a comment for the same moment in the book, which for me was at 67%... but 79% for them!

When trying to think of a way to solve that, I landed on the same suggestion as Jaina: an additional "What chapter is this comment about?" box, which answer would show before unlocking a comment, would help make sure we're all on the same page (pun intended).

I'm guessing this issue would be especially common with classics, since that's the type of books where there is the highest chance of variation in the actual content through the addition of introductions, notes, etc. As an example, my copy started with 50 pages of introduction in roman numericals; the title of the novel was on page 1, with the novel ending on page 520, followed by 50 numbered pages of endnotes. As a result, the story started at the 0% mark and ended at the 92% mark. Now, on a copy where the introduction would be numbered, but that would use footnotes instead of endnotes, the story could start on the 10% mark and end at 100%, and that's only one other combination out of many!

Yes, we ended up doing the same thing for a buddy read I just finished. Our percentages didn't line up so, to avoid spoilers, we opted to state at the beginning of the comment where we were in the book. However, this didn't solve the issue of comments remaining locked for portions of the book I'd already passed.

For example, we were reading The Two Towers by J.R.R. Tolkien, and, in the latter half of the book, when I marked that I'd finished Chapter 2: The Passage of the Marshes on page 218 at 62%, someone else reading the e-book left a comment at 64% where they'd just finished Chapter 1: The Taming of Smeagol. So for me, comments were not current and I ended up having to wait for them to unlock and then read them in retrospect.

Thank you for this suggestion! Just to check — are you both tracking against your specific editions within StoryGraph? Had there been any comments before this point for you to spot the discrepancy?