Some commands from the cheat sheet seem to be outdated and need some love. This wiki aims to list all commands and check if it still works. If not, idea is to get the working command and update the cheat sheet with a PR on GitHub.
So, someone can test, report it here. Someone else can find the solution and another person can create a PR 
Development Commands
Diagnostics
Home Screen and Compositor diagnostics
Calling diagnostics
Backup Diagnostics
OS Update Diagnostics
Browser Diagnostics / Debugging
Multimedia debugging
GStreamer
Camera
Email / Active Sync (e-mail) debugging
Restart sailfisfish-eas doesn’t work:
Written command:
systemctl --user restart sailfish-eas
Restart System Services
Repository handling
Package Handling
Clearing, Importing and Exporting User Data
Phone
Messages
People
Exporting contacts doesn’t work:
Written command works only with locally stored contacts:
devel-su -p vcardconverter --export contacts.vcf
Fix with:
pkcon install nemo-qml-plugin-contacts-qt5-tools
contacts-tool collections | awk '{print "vcardconverter --export " $2 "_" $4".vcf, $2"} | sh'