Your Fortnite to Apex conversion are matching 360 distance between the games. This is a method with does not take FOV into account. But when you convert to osu you're using MDH 100% (360 distance is not available for 2D conversion for obvious reasons), which is a FOV based conversion. And since the FOV in the games are different you will get a different result.
Also you're FOV in Apex is wrong. You have selected config file as the location, but entered the in-game FOV. This makes the FOV calculation incorrect. Switch Location to In-game and it will be correct.