I have a book that has implied roman numeral pages, (i - xii) but the table of contents only lists the implied pages for the map's pages of x, xi, and 497. Does the brl copy of the contents page need to include all implied preliminary pages?
No; you do not add items to the print table of contents. Braille it as it appears in print. You will still have those pages in your braille document - and should note those pages on the title page - but follow print for the contents.