The basic problem: Selecting octaves is "sticky," which means that the same fingering can yield different notes at different times.
For example, suppose I play the following:
A (left thumb in center position, and left index and middle fingers down)
High D (left middle finger down, all others up)
High A (left thumb in top position, left index and middle fingers down)
High D again (left middle finger down, all others up)
When I play high D the second time, the Sylphyo has remembered that my thum was in the top position, so that D sounds an octave higher than the first one.
This behavior is un-recorderlike, to say the least!