you actually need to add those lines into conf.ini, at the end, before you can start adjusting them.
you might need to create a new section at the end, if you don't already have one, with the heading -- [Mods]
so, it will look like this:
[Mods]
TracersPlayer=400
TracersAircrafts=300
TracersWorld=100
TracersWirbelwind=50
then, you can start adjusting the values until you are satisfied.
also, with effects mods, don't be scared to mix 'n match them, until you get something you are happy with.
thing is, effects mods are very much a personal taste thing, which is why a lot of guys use this mix 'n match option.
as long as you know how to rename mod folders so that they have priority in the loading sequence...
this is why many new mod folders start with a '0_Effects', or such. with the '0' in front, it will load before another mod which doesn't have the '0'