Instruments.xml info for 5 string banjo (pluck.banjo) is incorrect.
Most 5 string banjos have 22 frets. Recently, builders have added 2 more (some times). The current frets setting in instruments.xml is 19 for "pluck.banjo". This should be changed to 24.
The note ranges should also be changed to 47-88. Tuning the low string down to B (47) is common. If you tune the high string like a guitar (E) then 88 is the note at the 24th fret.