The stats probably read at the lower cooler section of the heater, so you’re correct in that you see the output temp being much higher than the displayed set temp.
What you need to do is dial these back in live play, to get the output temp that you require, using the stat as a ‘volume control’ vs using the markings denoted on it.
I’d still say to add a primary pump and tee off a recirculating loop, maybe via a 25L or 50L volumiser, for the best long term functionality. Should see much fewer on / off switching events and max out longevity of the controls.
I’d defo keep the TMV and manifold pump as is, for ultimate floor temp control. You’ve already paid for and installed them anyways.