I've never gotten UNetBootin to work to actually make a bootable usb, the only program I use to write an iso is ImageWriter (usb-imagewriter) it hasn't failed me once.
Hope I understand what you mean about checksums (still a super linux and computers in general newb)
Mate 32bit: 4ebcf5ae6268bec0b26a10143e4f7b55
Mate 64bit: 90dcb75e716a791429eda16374c5ab31
Cinnamon 32bit: f0153fa28ae5a4014962046fc66156a6
Cinnamon 64 bit: 82527fd02e6f0b8458c59488a2681396
And I understand wanting to stay away from Ubuntu, any Ubuntu based OS (sadly including the Main Linux Mint) has always hated every computer I've owned.
Hope that helps somewhat