The video processors were 16-bit in the Pc-Engine/TG16.One 16-bit HuC6260 video color encoder and one 16-bit HuC6270A video display controller. You could say alot,but the Pc-Engine has some remarkable looking titles that the Snes didnt touch.. Yes,most tend to be on cd format,however the cd-drive did not add extra processors,just a new storage format and cd-audio for the music. Kabukiden,Legend Of Xanadu II,Rayxanber III,Forgotten Worlds,Gradius 2 and the Neo Arcade Card ports. There are many others,this doesn't even scratch the surface.
The Snes had alot of power,but to say it could blow the Pc-Engine away graphically is a mistake. Its only real advantage was Mode 7,if you consider it a advantage,and a better audio design,until you pit it against a Duo cd title music wise. What it could do graphically its cpu could not manage to keep up with anyway without issues if the game was pretty complex. It was painfully slow. The Pc Engines 8-bit main cpu was very very fast and very efficient. For a system a couple of years behind the Snes,it had no issues keeping up with providing the same kinda quality titles as the Snes and Genesis,esp graphically.