Me too. Seriously. Displayed material has a blank line preceding. This announces to the reader that the nature of the text has changed. No problem with that when the displayed material begins on the same braille page. But if text ends on line 25, there's no space for the blank line except at the beginning of the next page.
I use that as my starting point. When I have a specific situation as I'm transcribing that I can't figure out, I look in Formats for information and hopefully, an example. I don't think there is an absolute unifying principle for this or even a hard and fast procedure for all cases. With situations like this I find it best to work on a case-by-case basis. And you're always welcome here.