So the mod is supposed to increase your magicka by 4% each time you level. I notice that it also adds a permanent Fortify Magicka active effect to your character, however the effect is 0.0 x INT... so it isn't doing anything.

I am level 2 on a new char and my magicka is 42 and my INT is 42. Starting magicka was 40, 4% would be 1.6. This means the mod rounded up to 2, to make my magicka a total of 42, which means the mod is working correctly.

My question is, why is there the active effect if it isn't doing anything?

I may be missing something, but it looks to me like the script "LeveledMagicka" could easily be rewritten to not use that zero fortification (leveled_magicka_000), as it really isn't used for doing anything that I can tell. It also may be the case that it is supposed to be removed, but isn't because of the structure of the if/elseif/endif block that removes old spell effects. It's also unclear why some of the fortifications have values that don't fit the pattern of other fortifications (leveled_magicka_100 has magnitude 100, leveled_magicka_200 has magnitude 216, leveled_magicka_300 has magnitude 301, leveled_magicka_400 has magnitude 400 ...).

Well, the author does give his email, so perhaps he could come to this thread or email back the answers.