It used to work well, but recently I tried to download the English audio of some shows and it starts to save multiple files undefinitively. (Files ending in "ad" after the first incomplete one).

Same thing here.

Same here!
The problem is when you have the audio description option.

Workaround: execute in devtools "document.audios = document.audios.filter( a => a.NAME.indexOf('[') == -1 ) ". This will remove the audio descriptions from document.audios (filtering by containing the "[" symbol). It will work after this.

The issue for me is when I try to download audiotracks in different languages

With the trick above, I managed to download audios in other languages other than English as well.

How do you do the trick?

Using Chrome, access disneyplus and open the screen where all audios and subtitles are shown. Then, right click with you mouse anywhere and choose the last option of the context menu: "Inspect". This will open a window usually on the right side of screen. Then, open the "console" tab and past the code above and hit enter. You can know click the download as usual and it should work.