That's what we're here for.
Let us know how it goes, or if you have any more questions.
Terry is correct that the Voreto can sometimes be fixed by disconnecting the braided wall hose from the valve and using a needlenose pliers to extract that little filter from it, washing said filter, and reinstalling. I think we're all thinking that a little construction gunk may have gotten in the line when your plumber moved the wall valve, and might be blocking it right there. (That's one reason I mentioned that you should see if you have pressure/flow at the end of the braided hose. I was also thinking that any gunk might just drop out the bottom of the valve, if there was some right there, when you disconnected the hose.) So...when you check for flow you might also check that little filter. I'm guessing that the filter itself is not clogged, if only because the problem has been there since it was installed, but it's worth checking. And if that doesn't fix it, then, yeah, put in the Korky 528MP or get yourself a TSU99A.X from Toto. (Only get that TSU99A.X if it's free; there's no real advantage to using it as it is functionally-identical to the 528MP. It just gives Toto a branded product that they can sell as a replacement part to people who really, really want the "manufacturer's" part. )
I think that Terry may be the impetus for the TSU99A.X by the way. For years, he has carried the 528MP valve on his truck so that he can fix/replace the fill valve on any Toto with one universal valve; instead of carrying a variety of different Toto valves with different heights and refill ratios, he carries the 528MP (now he carries the 528PRO, which is the pro version of the 528MP), leading to fewer parts on the truck, smaller inventory, etc.
Terry repeatedly mentioned this on the web site and repeatedly mentioned that the 528MP was a perfect replacement fill valve for Toto toilets, and was made by the manufacturer of many Toto fill valves, Korky. Meanwhile, at one point, the "toto store" on the manufacturer's web site must have had 30 different fill valves listed. Toto was carrying all that inventory, and having to take the people time to help customers pick the right replacement valve for their toilet. The Toto folks are smart, and -- I am convinced that it's as a result of Terry, whose forums they and the Korky folks do read -- what they did was commission Korky to make a Toto-branded 528MP variant that would work on ANY floor-mount Toto. Because the Toto people are sticklers, and serious about saving water, what they did was to include a table that lets you set the height of the valve to exact factory specs, rather than eyeballing the level of the fill line, and a little gizmo that lets you set the refill ratio exactly-precisely to the exact percentage for your toilet, which is a little obsessive. With the 528MP, you eyeball it, and that's really good enough. And saves $10 on the price of the valve.
Anyway, good luck! And keep us in the loop!