It may get new values, but usually Homey does not trigger when a value remains unchanged. It will probably be the same for you. You also mention 3 min per reading. That could be a really short, really big waterflow, or a long and low one. But the more polling you need, the more load on Homey. But I think the application I mentioned will do about what it can with the data you got.
Your solution sounds very sophisticated, but a Youless combined with a water meter reader (usually pulse based, what I’ve got) seems to give more detail than what you’ve got. It also does flow calculations, so that may also be an option, albeit with less AI.
I use this: Water- of gasverbruik Monitoren? - Cedel webshop
With YouLess LS120 energiemeter - HAshop.nl for both energy and water. The [APP] YouLess, Enelogic, PVOutput - Belgian and Dutch P1 Smart Meter Reader does the water flow calculations.
