The label offset is also set to the right of the node. I wonder can we move it to the center/below the now?
I don't think so .. there are almost no options when it comes to labels ..
Indeed, there is nothing to set the offset yet.
But in the new version of sigma, you can still overwrite the default labels renderer with your own or add a new one, which makes possible for you to modify the offset as you want without having to modify sigma core sources.