Creating labels in D365 is a step back from AX 2012 because you can't create the label directly from the property or in code. Yuk.
The only trick that I've found so far is that, in the label file, when you copy (ctrl-c) a highlighted line, you're actually putting the full correct syntax (ie. "@XYZ:EventType", not just "EventType" from example below) in the copy buffer. That's at least a small help when you go to the property or code to paste.
Comment if you know of any other time savers.
P.S. I've been using a little clipboard tool to automate my label making while I'm currently creating labels for lots of fields that previously had no labels. I have the tool automatically remove spaces and some illegal characters. So, I'll copy the text that is to be made into a label, paste it into both the Label Id and Label fields in the label file, then copy/format/paste the Label Id field to remove all the spaces, then ctrl-s to save the label file line, ctrl-c to load it into the clipboard, and then paste it into the table field label property (or wherever). That's a convoluted explanation, but you get the concept. A link to the tool is below: