We are right now migrate from 9,14 to 9,40, using Open Interface Tables.
To migrate Proposals it is necessary migrate the workflow too?
If you want the proposal to transition from one step to another in 9.40 instance, then yes obviously WF needs to be present.
9.14 -> 9.40 us upgrade, what do you mean by migrate? Are you inserting data in a blank 9.4 instance? Why are you not upgrading?