I know I said I wasn't going to talk legal but I was curious so had a look at the TGA establishment act and it turns out you can't take civil action against the Commonwealth, the Minister or any TGA staff. So it looks like if they breach the 255 days nothing happens.
Relevant section is 61A at https://www.legislation.gov.au/Details/C2021C00376/Html/Volume_2#_Toc83632941
