If it is not found in the database please add it, the database is edited by users so if there is something missing feel free to add it to the database.
You can add a standalone recordings to the database by going to editing > add standalone recording or by going to the artist page and click add recording from the side.
Tagging standalone recordings is a little more difficult, install and use the “load as non album track” plugin. With this plugin loaded you can drag and drop the url for the recording in to picard to get it to load the information for you to tag. I have added an hour long dj mix as a non album track but you could also add this as a release if it makes more sense.
Feel free to add misc audio stuff as well. I occasionally buy audio books and add this information to the database so don’t think you need to be limited to music.