No, seafile does not support calendar and contact sync.
Where did you find this information? At least https://www.seafile.com/en/features/ does not list it.
As a very lightweight alternative for calendar and contact sync, I use https://radicale.org/3.0.html . It is not very feature rich but might be enough.
It's open-source, you can find the sources for the community edition here: https://github.com/haiwen
A comparison of the features can be found here: https://www.seafile.com/en/product/private_server/#feature-list
Managed to figure it out, with a bit of work. Apparently, file changes made on the NAS end(mounted via CIFS) are not reported to the Seafile.
The key was to change the Sync Interval. While easily doable using the GUI, there is no easy way to do so via CLI.
From what I understood, this could be achieved in the seafile database but I am not too familiar with it.
So, I ended up using SSH X11 forwarding in order to invoke GUI on my client machine to change above sync interval on CLI client.
Very bizarre method, yes I am aware.
My hope that at some point Seafile incorporates this setting into the config file that can be easily changed. That of course IF CLI is something they'll be supporting going forward.