So you have a lot to say for someone not flying the plane in MSFS… If you just watch reviews you will probably be mislead (on this very plane) since updates have make this plane from “meh” to “ok” with solid work on what was a problem for customers.
=> customer support on this plane has been serious, real and evolutive towards what customers wanted.
If you are not a customer you will have missed that very important part.
Bill’s TB-21 does have some quirks, like the visual mistakes you pointed. But it is great that someone knowing the plane inside out get Bill a solid feedback, which I think you should address that TO HIM NOT TO US, so everyone here can profit of your knowledge 
Also you need to take in consideration that MSFS is not XP11, and you cannot get the same “depth” in both sims concerning gauges support. But I confess I don’t know the real plane at all (just saw some on the ground).
That said, so far I have no plane behaving “correclty” on all fronts in MSFS, so it is hard to throw a rock at this one specificly and not at most of the other planes btw, the simgame is “brand new” (in the hands of Asobo) and really must mature a lot before claiming to be “a good overall flight simming platform” as revendicated initially (lol).
My review on this very plane would be :
For 25$, the plane is ok, not good not bad, just ok. Textures and external model are ok but need love, even since last update, I think people would like a bit of “pimp” on this…
The pit is good, with many gauges active, a working GPS and related AP (which is a good thing it works nowaday in MSFS !), a decent startup procedure (not realistic). Lighting in the cockpit at night is really good now, but shadows are still strange and edgy in some conditions.
There are animations and ground clutter as you would imagine nowadays.
Performances close to the actual POH when in flight (making it my fastest piston plane btw !).
Some gauges seems not to be related to a real value (to compare with all Carenado planes having more of gauges wrong…), and the turbo logic can not be followed as for all turbo planes in MSFS (Asobo’s part of that code is not exiting yet… Same with the prop RPM logic in MSFS still broken since release…), which is of course a bummer for this kind of performance plane, but it is still a very fast plane and the fuel consumption is on par with POH, speed at cruise too.
Sound set of the plane is not on par with MSFS’s default quality, but making a WWISE soundset is VERY EXPENSIVE and need specific work/ hardware (and of course the real plane), which I don’t think Lionheart had access to (both hardware and plane…).
The result of having the old sound set from FSX (I presume ?) is that there is no internal/ external sound set and that is a big issue for immersion when you open doors… Also the quality is a bit low (in some configurations you can guess the soundloop). That is btw true for most of the planes available for MSFS : only rare addon planes have a real soundset made for that sim !
I enjoy flying this plane in MSFS as I don’t have the M20R Ovation and wanted a performing piston, and I am very happy to see that the support and updating on this one has been better when the support of the Ovation has just been non-existant then worse.
25$ is for me “a bit much” for a plane in MSFS, considering the market and the new habits Asobo is trying to make (15$ for the JU-52 and a lot of “plane” for that price !). I think “old devs” still have very bad memories and fears of very low selling numbers, thus higher prices… But then Carenado, which is the big “plane partner” for MSFS, should also show a good example and get their planes in the good price range too ! But MSFS is selling millions of copies, prices will go down anyway.
If you have/ need/ want to get a fast turbo-piston plane right now in MSFS, this one is at that time a more solid option than the Carenado planes.
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