Gilpin and his team evaluated operational areas, team services, venues, ticketing, tournament budgets and host city operations for the Sept. 20-Nov. 2 2019 tournament.
"There are areas where the organising committee has not progressed as much as we would expect by this stage," Gilpin said in comments published by Kyodo news agency.
"We have reminded our friends at the organising committee that there is no time to lose with two years to go.
"The Japan Rugby 2019 Organising Committee recognise that they need to accelerate the selection of training venues," he said, stressing that the next two months would be critical to the success of the event.
Wednesday marks the two-year countdown for the event and Japan will mark the milestone by parading the Webb Ellis Cup in 12 host cities and the country's Top League clubs over 46 days.
"All stakeholders, including government and host cities, will need to continue to play their part to ensure a successful event that advances rugby on the domestic and global stage and shows the best of Japan as a host to the world," Gilpin said.
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Peter Rutherford)
