While there might be bugs in the calculator, none of the examples you give are bugs.
Everything is working exactly as intended, the calculator is giving you the correct sensitivity based on you setting. Nothing here is broken.
If you doubt the validity of any conversion, just try converting to and from a game that use any of the methods, and you'll see that it is 100% correct, bar rounding limitations.
CSGO for instance use MDV 133.3333% as default, as you can see it's perfectly calculated:
In BFV you can set the same USA value as MDV, and you'll get a perfect result:
The same goes for BO4:
PUBG use MDH 100%, again spot on:
If the conversion in your example makes CSGO feel too fast, well then you need to use another method. MDH 100% will be quite a lot slower.