A few things regarding making tonkatsu:
I used to make chicken katsu every day at a restaurant where I worked for three years and I still make katsu—chicken and tonkatsu—at home from time to time, and the method they've chosen to make their tonkatsu with here is incredibly inefficient.
Sprinkling flour onto a piece of meat is a really inefficient use of time. It uses both hands, and you're not going to coat the meat evenly. Instead, it's much better to dredge the meat in a bowl or a pan of flour.
The egg wash used between the flour and panko isn't just plain beaten eggs; water has to be added, or else the eggs with be too thick and gooey and will easily fall off the meat.
The breadcrumbs need to be ready ahead of time, and you need a lot of it, preferably in a bowl or a pan; you don't just coat the egg-washed meat, you need to punch meat down into the breadcrumbs or they'll very easily fall off.
And you should prep the bowls/pans of flour, egg wash and breadcrumbs beforehand; for food safety reasons, you don't want to be doing them one step at a time because you'll have to constantly wash your hands to avoid cross-contamination, and even with cleaning magic, that'll take time (and mana). The best method is to prep all the ingredients ahead of time, then have a dry hand and a wet hand, so that you pick up the sliced meat with the wet hand and drop it into the flour before flipping it and picking it up with the dry hand to put into the egg wash. You flip it in the egg wash with the wet hand, then put it into the breadcrumbs with the wet hand, punching it down and flipping it before punching down again with the dry hand. Then you set it aside into a pan or a plate and start again with the next one. Restaurants are all about doing things efficiently; you always have to work like you've got 10 other things to do, because you always have 10 other things to do, even after you've finished those 10 things, because 10 more things will need to be done.
"Breadcrumbs are spreading too fast" is not really a thing happens when you make katsu in a restaurant setting; the breadcrumbs are already pressed into and adhering to the egg wash and flour, and any breadcrumbs that would have fallen off would have fallen off into the pan or plate where all the katsu had been placed during the breading portion of making katsu.
Also, katsu are not typically made to order; they're usually made ahead of time and parcooked, then flash fried to hot to order. Chicken katsu can take 15 or more minutes to fry just to get to a safe temperature, and tonkatsu, in my experience, takes 10 or so minutes to cook through depending on thickness, and you don't want patrons having to wait that long for their food, especially if you're a busy place and want to turn the table as often as possible.
Again, author wants to write a cooking manga, but doesn't have experience working in commercial food service. Really annoys me.