I know this probably isn't the correct place to put this but no suggestions page exists to my knowledge.
I was wondering would it be possible to implement a command in the mod that allows the player to set the world type they are already in as a default world type, this would allow players to add world types with features that cannot be accessed with the mod the way its designed already (like how with cubic chunks the world types cannot have the cubic chunks feature enabled making the mod redundant, however allowing players to modify the worlds settings makes this mod redundant too)
If not that's alright, thanks already Terry!

So I think the answer to your request as you are thinking of it is it's not possible.

It's certainly possible to say make a button to let you copy the settings of an existing world into one of your default world gen presets: this would include seed, world type, and customization string, could even adjust the structures and bonus chest between enabled/disabled, and maybe import the data directory and possibly smart import some commands for gamerules and other known/common settings. However you will find in nearly all cases could have been manually configured. So while I think this is a cool shortcut to add it's not going to let you sneak a special configuration in.

It is also possible in the future I will add better lockdown like support, currently I already could inject data files into a world (this is really any file into the world save, except the level.dat) however this limits you from premade worlds since modded blocks require the level.dat data to be recognized.. thus some better logic is required to merge it into a new world. While this might capture any additional settings if the flag you wanted is in the level.dat you are also going to get the seed. (Maybe 1.13 will just fix this for me since the blocks are saved per chunk and not with global IDs)

Last if something is enabled using commands you may already be able to use the on world load commands, (ran once every time a single player world is loaded, or server is started) I intend to (probably in 1.13) change this to include more events (on world load, on first load, on player join, new player join, ect). This is really my goal to let pack creators use command block/mc function vanilla tweaks along side mods.. (thus far most use of this has been horders delight 1k setting the world boarder, and various packs using it to reload better questing each lauch)

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The last I heard of cubic chunks, and I never actually ran it, was the author didn't want it by default, and didn't want it a world type of it's own.. but wanted to force a new option on the new world screen... This is never a inter-mod friendly solution, and would require me to create logic specifically to integrate it. (The generic solution is make a new customizable world type, and if another world type is a subtype let the user choose and customize it from that customization screen)