Just getting the RFM right is challenge enough. Contract them to it though....and they provide....currently on draft 3....looking very good now.
The checklist should, however, always be the 'operators' preserve as the manner in which the aircraft is flown, crew numbers, CRM procedures, etc...etc...can all vary from customer to customer, and it is the operator who intrisically knows the answer to how the aircraft will be used.
My opinion, it is a big ask for the maker to cover all possible checklist outcomes, and in this litigious age, why would they?
Just be clear that your own checklist has all the critical ingredients.
I have seen the 'generic' 139 check list, which looks very good and obviously benetfits from the recency of the aircraft. The 109, however, has a great many different variants now and standardisation of checklists would obviously be more difficult.