User feedback
As mentioned in the README, right now there is no mechanism in place for letting the user know if tracking worked or not, but there is a hacky way I'm using in my own addon:
As you can see in my HandleSubRequest function, you can still send an essentially empty subtitles object, but adding a lang attribute makes it so that that text appears in the list of available subtitles for the user. You could send something like animeoOK or animeoERR based on the outcome.
I am not really using the sdk because I am doing everything on my own, but let me know if you want me to try creating a simple PR that tries to implement this in this repo (it would be a few extra lines in addon.js, at least based on a first brief read of the code).