Random general observation: Linux is like that. A lot of messages output that are meaningful only to the author and not actually indicative of a problem. So maybe justifiably alarming, maybe alarming but not justifiably so, maybe not alarming.
Fault isolation would be: temporarily reverse that change and just run /home from the main (eMMC) drive and see whether you still get the reboots and/or the journal entries.
Well, anything to do with DRM is more alarming when it does work. 