Ideally you should not convert directly between aims, and instead use the "All" selection which will convert all aims at once and make sure your settings stays consistent. The issue with converting between aims directly is that you have to make sure you set the correct hipfire sensitivity, FOV and so on so it actually matches your settings.
Also you need to adjust the conversion setup to match your preference. If you like the Legacy option, the default setting in the calculator is the one for you (MDV 0%). You should also match the hipfire FOV for both games whenever possible (meaning the Actual FOV, not the configured FOV value which will vary depending on the FOV Type).
This means that the 360 distance changes depending on FOV.
For instance in CoD 2019 hipfire the 360 distance stays the same regardless of your FOV, while in Back 4 Blood the 360 distance will change depending on the configured FOV. Some games will even change the 360 distance depending on the aspect ratio since it changes the FOV.