Time always changes a beer for sure, a wit though you tend not to wait on for too long, they're best drunk fresher than most styles.
It sounds more complex than it was to be honest. I built my own electric BIAB boiler system, with a controller etc. So was a simple matter of setting it to a bit over 45 degrees C, mashing in the wheat and oats, leaving them to sit for 20 minutes at 45, then turning the temperature up to raise it all to 65 degrees, then once it reached that adding the pilsen malt for the rest of the normal mash. A false bottom kept the bag off the element, and I stirred whilst raising the temperature to keep things moving. It's a lot more complex if you do it the "proper" European way, with decoctions etc.
If I hadn't of done it, my pump never would have coped with the gummy mess from so much flaked wheat.
Simpler route for you could well be to just mash at 67 degrees C (medium body mash), or use a lower attenuating yeast, if you want it a bit sweeter tasting. Trade off will be a lower ABV though with either method. I just about squeaked 5% (after priming) with mine with the low attenuating yeast, thanks to the step mash, 65 degree mash etc. Not always a bad thing though. Of course, that's assuming you think it's worth it for a bit more sweetness. If something isn't really broken, just not quite perfect, sometimes it's worth just taking a step back and shrugging.
Alternatively, double check your IBUs. Check that it's lack of perceived sweetness isn't rather the balance between sweetness from the malt and the bitterness from the hops, as that's quite simple to adjust by just using less hops at the start of the boil for lower IBUs.
