NP playback: Flute Flatterzunge collides with recommended notation

Gould (2011), p. says that flutter tounging should be notated as tremolo with additional abbreviation like flz. -
flz.tiff (10.6 KB)
If I do this, NP plays more a tremolo then flatterzunge.

Do the new extended expression maps offer a workaround for this?

You may want to consider uploading your images in PNG format rather than TIFF so that they can be viewed in the majority of web browsers.

You should not expect to be able to edit the NotePerformer expression map yourself; really this is something of a black box that is configured by Arne Wallander for best effect.