I'm in the start of my third season with Liverpool, and getting a good backroom staff is always one of my top priorities. I always manage to find 4.5* coaches and put together a pretty good mix of good coaches, but getting every single training category to 5* seems almost impossible.
I gotta say, I use probably half of my play time to search for good signings, both players and staff. I find that to be maybe the most interesting part of the entire game. Unfortunately, coaches' attributes are to a certain degree randomized (also when it comes to players becoming staff) from save to save, often making top lists of good backroom staff pointless. I use the search function for finding coaches, and apply the appropriate filters. So yeah, back to the original question: Has anyone managed to get a complete 5* coaching staff?
Here's a screenshot of mine so far: