I find that for getting my bus routes I use google maps.
maps.google.com
if you can access the site through the american or canadian version (as google geolocates you normally)about half of everything is in english. just set the city to chengdu and choose your start and end points. the bus route thing even tells you the number of stops so you don’t have to listen for stop names you don’t understand.
small thing I have noticed is that the site is not updated for line two of the metro for some reason.