The FGB shows that either meaning is possible, so use the Report a Problem button to bring it to the attention of the course creators.

You wouldn't use greann to say that someone was "in a good humour".

greann means humour in the sense of "funniness" -"I enjoyed the humour in that film" - Bhain mé taitneamh as an ghreann sa scannán sin.

Until a couple of months ago, the Irish course only displayed the speaker icon if there was audio available for a particular sentence. But then they tweaked the HTML code that is used for the exercises, and took out the filter that checked to see if there was audio available before they displayed the speaker icon - now the icon is displayed for every Irish to English exercise, whether there is audio or not.

The HTML code for the discussion pages hasn't been updated yet, so it still checks to see if audio is available before displaying the icon, so there is no icon displayed on this page - at least for now, as Duolingo seems intent on breaking all of the tweaks that accommodated languages like Irish that don't use a Text to Speech engine to read the sentences..