I call bullsh*t you know how fucking difficult is to made every one of that “inventions” no carpenter is capable of doing that just by hearing how they work even with blueprints it will take a sh*t ton of tries to get one functional prototype
The whole keeping it a secret is the dumb move.
Step 1 - Make many copies of the method.
Step 2 - Go to a shop that has business across the whole kingdom.
Step 3 - Ask them to spread the design everywhere and ask for a cut of their profits.
With that it would be odd for a lord not to have basic plumbing. What are the lords going to do to keep it for themselves then?
Also best to give the Emperor a free guide.
I mean if a man can heal a wound that should have taken over a month in a day then you have to know things are different, my guess is that since all living organisms need more food and better nutrients that the plants had to become stronger and have better resistances so you might not even need some of the things from earth but it also says the bamboo was just as malleable so i could be wrong in my assumption.
The best way to enjoy this book is to roll with it.
Something doesn't make sense? Roll with it! 10 different things don't make sense each chapter? Must be a new sort of logic in that world! Find out the MC who was a bodybuilder knows how flush toilets work and can explain it well enough for a medieval carpenter to recreate? Makes perfect sense!
Just shut off your brain and roll with it.