I got working the double-tap feature on Sailfishos 4.4.0.58 Vanha Rauma
You need mcetool installed on your device (pkcon install mcetools)
I got to activate LPM first:
mcetool --set-low-power-mode=enabled
mcetool --set-ps-on-demand=disabled
mcetool --set-lpmui-triggering=from-pocket,hover-over
Then I activated double tap and configured it:
mcetool -M show-unlock-screen (can be also -M unlock if you prefer)
mcetool -z proximity
mcetool -i enabled
mcetool -E enabled
In case you want Double tap almost always active you can set LPM with a very long timeout, like 100 seconds:
mcetool --set-blank-from-lpm-on-timeout=100
Remeber: Double-tap on xperia 10 ii works only if you have already glance screen (i.e. if you take it out of your pocket)