The ADS sensitivity in Titanfall 2 is not a multiplier of the hipfire sensitivity, but its own sensitivity. Also the ADS sensitivity scaling locked to 70, so any other FOV will result in a slightly different sensitivity than MDH 0% for hipfire.
The FOV shown in-game in Apex is not the actual FOV, but is slightly off due to some lazy coding. So in the calculator it's shown as a multiplier by default, so when you enter the FOV value from the game, the actual FOV will be shown in the output.