How are you checking the aspect ratios?
Every console preset that uses a bezel is set to 1.33 in the shader settings.
The presets are “boilerplate” multiple reference presets that share a common reference that defines the aspect ratio. It is virtually impossible for them to have different aspects.
As far as the “original” aspects go, it is my opinion that in practice they are irrelevant. When viewed on a TV, the consoles all used every pixel of a 4x3 television screen.
The physical aspect of the television didn’t magically change to accommodate the pixel aspect of the console.
The MSX is a computer not a console, so it may be that someone used a monitor instead of a TV.
All that being said, you are free to play around in the shader parameters if you feel the need.