I took the risk (of soft bricking device) and manually added a new screensaver
Code:
scp bg_ss07.png root@192.168.15.244:/usr/share/blanket/screensaver/bg_ss07.png
on KS using a cats
https://file.io/EUCuyowuOlKc (indexed/232 colors/1860x2480) and it worked well. So maybe there are no bigger changes to these part.