BUG: 387639
BUG: 388458
I'd consider it only as partial fix. Poppler forces us to use 24x24 pts, else we'd never get a match. Poppler silently ignores what size applications set in Poppler::Annotation::setBoundary or what comes from the PDF objects /Rect entry, in the case of an external writer. This should IMHO get fixed at Poppler side, or at least it should be clarified why forcing 24x24 pts was necessary. The PDF standard just says "readers shall provide predefined icon appearances for standard names: Comment, Key, Note, Help, NewParagraph, Paragraph, Insert" [12.5.6.4]. It doesn't say anything about a predefined size. It says, the /Rect entry defines position and size [12.5.2, 12.5.3].
Patch in F5620896 shows how poppler could help out.
Some further references to get an idea why 24x24 enforcement was done in Poppler: