Thanks for the reply. So if I do understand it right, if I set a remote calendar on two clients (notebook, desktop) under - lets say Thunderbird - and create a new appointement on the laptop, go online LATER and more later turn on my desktop - the appointement will be synced on the desktop ?
Yes this works just fine. Maybe Lightning has evolved since that report you linked in 2010? I'm using the latest version of Thunderbird, Lightning and the nightly of the SoGo connector and with this setup I can turn WiFi off, work offline, create or edit events and they get synced immediately as soon as there is an internet connection again.
You can set the sync interval for each calendar in Lightning or have it only sync manually. When you right click on a calendar there is an option called 'reload remote calendars'. So when these new/edited events would show up on your desktop depends on those settings, but the upload to the server happens immediately as soon there is a connection.