So the passive gives you 3m extra range (I'm assuming this refers to detection radius) before you can be detected and brought out of stealth. Currently, Magelight and Inner Light are said to have a range of 6m. Does this mean, as a Bosmer or Khajiit, you can technically be within 4m-5m of your target and not be detected?

I don't know if this link is still current but:

With Racial and Medium Armor bonuses
o Detection radius is approximately .65m when directly behind target. (4m-3m minus 35%)
o Detection radius is approximately 7.8m when directly in front of target. (15m-3m minus 35%)

Does this mean, against a player using ML or IL, a Bosmer or Khajiit in medium armor could still be almost point blank and not be detected, if they are behind their target?

It's late and I'm sorry if my post isn't coherent but TL;DR is basically: Can you subtract this radius from the detection radius ML, RML, and/or IL provide?