Hi Lucas,
It looks like that we added the note id to the wrapper in a later version of PDF.js Express, it looks like my original approach will work in the current version - 7.3.7. However, after looking more at the problem, I may have given you an unnecessarily over-complicated solution, I believe this code snippet should work in older versions:
instance.dangerouslySetNoteTransformFunction((wrapper, state, createElement) => {
wrapper.querySelector('.author-and-time .date-and-num-replies .date-and-time').innerHTML = state.annotation.DateCreated;
})
Let me know if that works for you.
Cheers,
Dustin