Hi,
if I have understood correctly, the plugin API is not yet in a stable state, and I understand that you are still improving it. You probably have plans about improving the documentation too.
I’m very new to this API, and the biggest issue for me as a newcomer seems to be that the TypeScript interface that you provide lacks documentation comments for most of the methods and properties it defines: obsidian-api/obsidian.d.ts at master · obsidianmd/obsidian-api · GitHub
Some methods/properties do have comments, though. In my IDE (WebStorm), I use Quick Documentation along with auto complete very often to bring up documentation comments about methods and properties whose behaviour I’m trying to figure out. When the docs are empty, it makes it quite slow for me to learn the plugin development.
I have done programming on other projects and languages for a long time and I do know that writing comments is something that you don’t always have time for, and documentation can never be perfect. The API is large and I’m not expecting it to be documented at one time over a night. So, I do not mean this post to be a complaint 
.
I will continue my research on this API. 
P.S. Sorry if this has already been discussed about. I was not lucky with a quick search.