Easy.
https://www.pianostreet.com/Graded_Pieces_All.xls(Torp’s graded pieces excel spreadsheet)In the link mentioned above you can find the rating of many pianoworks. Satie is rated at level 6. Although Satie may be played slowly, the jumps make it more difficult. As far as I know I would think 6 is more realistic then 3.
Satie is rated at level 6
To my opinion, 'rating a composer' is a bit nonsense. Its like saying, Winter wind etude from Chopin is easy because he also wrote the Raindrops prelude.
Btw, can you really take a grading system serious if it grades Chopin's Sonate no3 op58 only 1 more difficult than a gymnopedie from satie?