The reason I purchased Newzik is the ability to transpose scores. However, in many cases, after transposing a score, the directions of the stems is just wrong. In other words, stems, even above the staff, point upwards instead of downwards where they should be.
We are currently refactoring our MusicXML render so as to make it more flexible and accurate. In a very close future, you won’t notice this imprecision anymore after your transposition. If you want to provide us with details, you can write to us at email@example.com