After each crash, I would peruse the syslog only to find
indicator-application-service acting up for several lines just before each
crash, saying something about how there was already an instance running.
"indicator" does not occur in the syslog you attached.
Come to think of it, the RAM may very well be the issue.
And, yet, you go on and on on how the whole free software movement is the
reason for the problem you face.
The seller may have upgraded the RAM before reselling the unit to me. No
matter; I'm not going to downgrade the RAM merely to make it usable, it would
make more sense to fix the bug.
You do not fix a defective RAM stick. You remove/substitute it.
Where would Memtest86+ be logging its output to, if anywhere?
Memtest86+ is launched from a bootloader (that may be that on a live ISO).
It is a tiny operating system dedicated to testing the RAM. It outputs
errors (if any) on the screen, which then turns red:
https://upload.wikimedia.org/wikipedia/commons/5/5d/Memtest86%2B_15_million_errors_2017.jpg
Run for a whole night.
