Upvote:5
The timetable image you have is correct. The bus page on the official airport website links to this website for Itami Airport. This website has the same timetable as the image above. Additionally, the route search (on the same page) for "Transfer to Osaka International Airport (Itami)" suggests buses which correspond to the timetable.
The Tripadvisor thread is 6 years old, I suspect the timetable changed during COVID-19.