Yes code always needs to be handled by code editors, not the infamous Word or such.
Ah, we learn every day, I didn’t know you’d have to save the flow export with it’s original name 
It was exported as Poll for firmware updates.homeyadvflow.json
When I remove the .json part prior to importing it, it is grayed out. I could import the flow on my 2 other Homey’s just fine with the .json part in the name.
“aflowname” was just a placeholder to use your own flowname. But apparently I have to pass the original flowname with flow exports. Thanks for the heads-up.
Unfortunately Homeyscript limits the owner’s options;
The firmware auto-update toggle and the backup enable toggle are read-only.
So, you can check them, but not set them.
You’ll have to request for less tight Hscript permissions at Athom’s.
However, apps can have more permissions, so returning to your original request:
if possible at all, and dev Geurt likes to extend the sysInternals app with Toggles for:
enabling Firmware auto-updates,
enabling auto-backups and
manual firmware updates,
we’ll be able to control it with flows.
Getting the timestamp is possible with this command:
const lAstbackup = await Homey.backup.getOptionLastSuccessfulBackup();
log('Last succesful Backup:', lAstbackup.value);
Compare the two timestamps to get the ‘how long ago’ info.
With the tip from @smarthomesven I added the last changelog to the flow;
For Pro 2023 and up:
For Pro 2019 and earlier:
