My concern was less losing Data and more corrupting the filesystem itself due to sudden loss of power. And while I frequently cloud-backup the most volatile important files, and backup my homedir to an external hard drive, I don't have an image backup of the VM outside my laptop, and don't have a backup of Windows itself (the host OS, which I mostly just use as host, plus Excel and occasionally non-Linux browser modes).

OTOH the new battery finally arrived! So I'm back to a more normal life. I'll leave journal=data on the Linux FS, but I replaced 'sync' with commit=1.