SHENZHEN airport officials and representatives of the Hongkong Association of Freight Forwarding Agents (HAFFA) have met to discuss potential problems which could arise in the future with forwarders who want to do business with the airport. Because more of its members are looking at doing business across the border, HAFFA has set up a Shenzhen six-man airport sub-committee. The airport is ''going international'' in a couple of months. In the last year, a number of Hongkong forwarders have opened representative offices or formed joint ventures in Shenzhen. Others are waiting in the wings, awaiting developments. ''The meeting was very amiable,'' said HAFFA chairman Walther Nahr. ''They listened to the points raised by HAFFA and are now discussing them in-house before coming back to us.'' Issues concerning Hongkong forwarders are possible delays at border crossings, bonded warehouse facilities and the issuing of air waybills.