I have an idea for a script that was inspired by an album by a virtually unknown band. In a perfect world the script will eventually be produced and soundtrack scored by the band’s music. But let’s take things one step at a time.
Do I have any right writing a script inspired by the words and sounds created by someone else? Do I have any right borrowing titles? Do I have any right writing their music into the script? (I know that’s normally frowned upon anyway.) I think you get where I am coming from. I don’t want to write a script heavily involved with specific music unless I know my rights.
You don’t have any right in a legal sense, but that shouldn’t necessarily be your first concern. If this is the script you really want to write, just write it. Just make sure that on the title page or a page thereafter, you give full credit for things that aren’t yours.
Obviously, if your script can’t be made without this band’s music, you won’t be able to sell it until they’re handled. But by your description, it doesn’t sound like the world is breaking down their door, so it’s always possible they’ll read your script and say hell yes.