Every transaction for a charity needs a fund. The blank fund (equivalent to fund 0) is set on the transaction by default and has no way to change it before posting so that the transaction of the bank charge has to be edited after posting.
It should at least be taking the fund set for the purchase payment itself (it doesn't).
Another case of poorly thought through Charity needs and adjusting the standard package to those needs. Clearly the fund field is ignored for non charity users and is left blank (aka treated as 0).
When it came to using the bank charges field of a supplier payment it was clearly forgotten to pick up the fund id set resulting in a "feature" (as the glossary of an Apple ][ manual defines a bug as described by the marketing department).