Update. Good news, and bad ones.
First of all, data copy went beautifully wrong. The destination folder was wrong, but data has been copied.
If you’re browsing into filesystem of a detached hard drive from Synology SHR, if you find a tempting @eaDir/sharename that’s not the directory you’re looking for. I know by sure because every file was copied from the XFS drive has been put there.
The “right” path should be /volume1/sharename. I found the same path during my tinkered wanna-transfers, but i was not able to write to that directory. Shame on me, now i’m looking for a way (SynoCli Tools) to use mc on the Undead DS212j. Hoping that mv won’t take that long…
Yes, you’re right, I don’t know how to correctly use mv from SSH. Better safe than sorry the second time…
(and mc worked like a charm…)