The file /lib/systemd/system/aliendalvik.service does not exist (sorry if I was unclear about that). The commands you suggest give
[root@Sailfish nemo]# systemctl status -l aliendalvik
Unit aliendalvik.service could not be found.
[root@Sailfish nemo]# pkcon search aliendalvik
Available aliendalvik-1.1.0-1.2.1.jolla.armv7hl (aliendalvik) Android App Support
Available aliendalvik-configs-10.0.57-1.4.1.jolla.armv7hl (aliendalvik) Android App Support configurations
Installed aliendalvik-system-10.0.0.58.2.1-1.5.1.jolla.armv7hl (installed)Android App Support system image
So it seems to me the aptd service failed to re-install aliendalvik and aliendalvik-configs because of some timeout during the update to sailfish 4.3.0, whereas the image to be run does exist:
[root@Sailfish nemo]# pkcon get-files aliendalvik-system
…
Package files
/etc/gbinder.d/alien.conf
/opt/alien/build.prop
/opt/alien/system.img
So I did pkcon install aliendalvik, and systemctl start aliendalvik.service, and now my apps work! Thanks a lot for your help.