They use the method I was testing with the purple fern that some people helped me with, and if that crashed your game then these might too (affected a very small minority of people - two to be exact - and without harm), but you can avoid that by making sure you have downloaded all four of the prison, hospital, school and highschool main controllers and have them in your downloads directory.  They're very small files and it's not necessary to actually put them in the game in order to avoid the risk, just as long as the game has read their ID numbers into memory.   As a matter of convenience, always save the game before buying any new objects from the catalogue, so you don't lose much playing time if there is a crash.  I am using the method because it save loads of processing and avoids slowing the game more than necessary.