I am requested to act as a correspondence for Duion, here is his message:

You did not delete all of Duions submissions and his comments are also not anonymized, they show as "Duion (not verified)joined 0 sec ago". Additionally you did not only not anonymize his posts, but publicized his IP adress which is personal data, which is legally even more critical than just a nickname.
And Duion said he wanted his account and all data deleted as he said here, which you quoted yourself: "I hereby request the deletion of my Opengameart account https://opengameart.org/users/duion all data associated with it. According to data protection law I have the legal right to that. You don't offer a method for that, so I just edited my contributions, but now since you banned my account because of that, I want my account and all contributions deleted, since I don't want to be associated with any of that anymore. I write from a second account, since you do not provide any other way to contact you. "

Edit: some minor mistake. 2nd edit additional links from him latest message.

Also he added he found those files which are still not yet deleted:

https://opengameart.org/content/fishtailpalmleaves
https://opengameart.org/content/ivy-leaves
https://opengameart.org/content/fabric-grey
https://opengameart.org/content/fastgras01
https://opengameart.org/content/leather-black
https://opengameart.org/content/ocbunkertextures
https://opengameart.org/content/occonstructtextures
https://opengameart.org/content/ocolymptextures
https://opengameart.org/content/concrete01
https://opengameart.org/content/syntdirt01
https://opengameart.org/content/syntfantasy01
https://opengameart.org/content/syntmetal01
https://opengameart.org/content/syntmetal02
https://opengameart.org/content/syntmetal03
https://opengameart.org/content/syntmetal04
https://opengameart.org/content/syntmetal06
https://opengameart.org/content/syntrock01
https://opengameart.org/content/syntheticsand01
https://opengameart.org/content/synttiles01
https://opengameart.org/content/synttiles02
https://opengameart.org/content/synttiles03
https://opengameart.org/content/synttiles04
https://opengameart.org/content/syntwallpaper01
https://opengameart.org/content/syntwood01
https://opengameart.org/content/syntwood02
https://opengameart.org/content/syntwood03
https://opengameart.org/content/wall-of-old-stones-mk2
https://opengameart.org/content/grate00v2
https://opengameart.org/content/williamwall01

I am helping him to find any additional content which are not yet deleted as he has obviously a bit bigger trouble getting his message out. So far from my result when I tried to search for his name or related to his game project under all art assets I haven't found anything made by him at least not according to the provided search function here, the only results I have from him is that there is a lot of places under several art assets were his comment are still visible for the public which shows as "Duion (not verified)".