I strongly feel that users need to be able to name the country they identify as from the way they want to. So a solution should put that as the priority, not who the arbitrators are. Since it is easier to ask Dreamwidth to change a list if something is missing, rather than the U.N., why not populate your initial list from a source like the U.N., but say you will edit it for whatever people need added. Scotland and Taiwan should certainly be on any extant list.