I really hate coming to her defense here, but I've rented long term and have made improvements, particularly to the garden of that property. I spent a lot of energy, time and money on it and it was worth it, because I did live in the place for a long time.
I also don't think there are nearly as many regulations as people on this thread suggest about what you can and cannot do as a freelancer in rented accommodation. Many YouTubers work out of rented homes and film them - as far as I know that's totally fine. You mostly only have to clear it with your landlord and insurance if you are using accommodation to host client meetings, etc. If you are just doing something on your own, you should be fine. It's also not a commercial kitchen in the sense that she's cooking food to sell, so I'm pretty sure hygiene and health and safety regulations don't apply to her.
Not saying she's not manic and that this is necessarily a great idea or that a can of spray paint will hold those wooden boards together.