[Karellen]

There is an option to add IMDb ratings with this Add-on. I'm not sure if this Add-on populates the IMDb rating info in the database after scraping the library. If it does, it does not seem to be working with Leia.

If the setting Default rating from or Also add IMDB ratings are enabled then the IMDB rating is stored in the DB. Depending on which settings are used, it may not be the default rating. (but probably not a concern for your skin, as it displays multiple ratings). I have just tested with last nights nightly release, and IMDB ratings are downloading.

I'm not 100% sure on this one, but I believe entering your TMDb API Key here is what allows The Movie Database scraper to fetch the TMDb ratings and images.

Nope. TMDB don't have a user level API. They are developer API's. The scraper should be able to fetch TMDB ratings and images just by using Kodi's integrated API.

Note: This works with Krypton but not with Leia. I am not getting IMDb ratings with Leia.

Working here. Just tested it using KodiSetup-20190118-9a49e6c1-master-x64

In case you are not aware of this Add-on for IMDB ratings... https://forum.kodi.tv/showthread.php?tid=316342 Might be an idea to speak to the developer about extending its abilities for the other ratings like rottontomatoes, metacritic etc...