@Zethalion first pointed it out to me here

On further inspection, it seems that the code to actually configure effects, and the code to actually apply said effects, aren't in place yet.

How easy would it be to actually do it, and should I?

Ok... but effects are coded here.

But you can't exactly add or remove effects to a worldborder, can you?

https://github.com/ForgeEssentials/ForgeEssentials/blob/develop/src/main/java/com/forgeessentials/worldborder/CommandWorldBorder.java

I'm working on some overall improvements as well - stay tuned.

way too many options

Oh, I've found a way to solve that problem ;)

Believe me, I am hooked to this. Effectively the WB is ineffective currently.
Good luck coding @luacs1998 !

@luacs1998 there is just no command config, because there are way too many options 😄
It is intended for the json file to be edited which is why it is created with all available effects already added.