Plumbing at “water closet”

Hello. It is good to know that we have a lot of educated installers (mostly from youtube) just a mystery why we still do not have hot water. OK,  enough of jokes… Last Saturday I took a few photos of our “water closet” and I talked to an my friend plumber I have known for several years. He is willing to fix it for us so that it will work once and for all. He won’t want anything for labor, I’ll take him or his son for the ride next season. Just the necessary material we will have to be paid (but we will have to do anyway). If John DeRosa will bring a new tankless unit, that’s great, he can install it. Tell me what you think about it. Petr