Confirmation on my part that the Samsung A3 update to the e-0.19 version went well using a TWRP recovery to flash the new zip file. No problems apart from the Android error message that existed before.
However, the update on my main device - a OnePlus 6 - was much longer than expected. After the initial download there was a progress bar indicating the installation was taking place, but after a second message about “preparing packages” or something to that effect a further progress bar advanced at a snail’s pace and took well over an hour to complete. As there was no reboot to recovery and this is an A/B device I assume that the installation as to the alternative slot and then I was finally able to reboot successfully to the updated version.
However, as I have related separately, this new installation replaces my TWRP recovery with /e/'s own version and unroots the phone. This made a reinstallation of Magisk a major undertaking. See my post.