One was nicely pointed out, after a lot of searching, by direc85 and it was the USB mounting glitch. Wouldn’t go so far as to call it a bug, because the lower power usage on older Laptops has it’s uses. Anyway, check the file entry in:
$ /sys/module/usbcore/parameters/autosuspend
If the Value is set to 2 change it to -1 instead.
The second one is during the flashing process. After SFOS is correctly installed, fastboot throws out an Error like:
FAILED (remote: 'Requested download size is more than max allowed')
In this case just run the fastboot command as indicated by the script and add -S 512k like so:
fastboot -s DEVICE-SN -S 512K flash oem_a ./SW_binaries_for_Xperia_Android_11_4.19_v9a_lena.img
The DEVICE-SN is explained in the HowTo on how to retrieve it. The -S 512k will convert the *_lena.img into 512 kb sized sparse bundles, that then are copied gradually over to the Sony Xperia III. It is a little slower in progress, but gets the job done.
Lenovo T430 running VOID Linux if that is of any interest.