Hand Bell Range Is Incorrect
The convention for hand bell music is to have middle C in the bass clef, along with its sharp. The treble should have D and its flat. This would move the "Low Hand Bell" max range from 60 to 61 and the "High Hand Bell" min range from 60 to 61.
And technically, the instrument range is from C1 to C9 (so would need to be expanded on each end); but the common limit is the one that is currently set.
To further complicate matters, middle C (normally C4) on a handbell staff is actually C5; I'm not sure if you'd want to transpose the staff to reflect that fact.