Hi, I'm glad you managed to find the solution after all! What you do is indeed correct.
I wrote the code that the 'label' and 'url' both show the same value 'url' because in Ren'Py you can't see the link where you're going to be redirected to unlike a browser, so for someone who doesn't want to click on a link they don't trust they can at least type it manually. Admittedly, it's not exactly pleasing for the UI, or it can take a lot of space too.