Yeah I know you do. Ideally for consistency everyone should use apps in English because that's what all programming/scripting languages are in, but I know some people prefer to use their native language if it's available.
display text is the text used to make characters speak & is displayed above the characters head, unless the text is forced to a different position with the setTextPosition hook.
display object text is when you link a text to a scene object or interface button. the text remains on screen until you tell it to go away with another action part.
display narration text is well narration text.
background is when you tick the checkbox on the display text or narration texts & the text gets played in the background independently from the action part list & can't be skipped with left click.