When borrowing extended chords, Hookpad only includes the highest chord extension into the roman numeral, regardless of whether any of the other notes are altered. For example, when you borrow a tonic seventh chord from Mixolydian, Hookpad correctly indicates that the chord has a flattened seventh, but when you borrow a tonic ninth chord from Mixolydian it is just displayed as I9.
If the highest chord extension happens to be altered, Hookpad does put an accidental in front of it, but that still results in an incomplete chord label. For example, borrowing a tonic eleventh chord from Lydian results in the chord label I♯11 when it should really be I9(♯11).
