If a constituent has a current solicitor/fundraiser relationship (i.e. no "date to" filled in), there should be a setting to automatically add the solicitor to every new gift from that constituent.
This is currently only kind of possible during batch entry (in database view at least) where as you tab through a gift row, any relevant assigned solicitors will auto-fill. But for imported gifts, the solicitor/fundraiser does not get added, which makes NXT reporting by fundraiser impossible, since insights and gift lists work off of gift solicitor and not constituent assigned solicitor.
Alternatively, make it possible to filter on assigned solicitor/fundraiser in a gift list even if that solicitor isn't on the gift.