EDIT:

After ages of trying to track down which mod could interfere with this mod
I finally found it.. Terraqueous (terraqueous-1.10.0-1.2.14.jar) interferes with this mod, if your mod is loaded while that one is, the world generation just hangs.
I also reported this on that mods issue tracker, see link below:
ShetiPhian/Localizations-and-Issues#22

Unfortunately there are no error logs or warnings regarding this mod,
all it does is, hang on world generation with YUNoMakeGoodMap in the mods folder.
And without it, my server generates just fine.

Maybe its a incompatibility with another mod? I added a gist link to the whole list, its big though.. (see bottom)
(RFtools? see the instance=null message)

Maybe is a config setting I have to set in another mod or your mod? I also attached the config. (see bottom)

Any help is very appreciated!

Here is some logs, there is unfortunately not much:
With YUNoMakeGoodMap:

[13:23:04] [Server thread/INFO] [Actually Additions]: No WorldData found for world 1, creating...
[13:23:04] [Server thread/INFO] [Actually Additions]: No WorldData found for world 0, creating...
[13:23:04] [Server thread/INFO]: Preparing start region for level 0
[13:23:04] [Server thread/INFO] [STDOUT]: [mcjty.rftoolsdim.dimensions.RfToolsDimensionManager:getDimensionManager:308]: instance = null
---
(And here it hangs.. forever. it does show ~10% cpu usage and some disk I/O but nothing major and it never ever shows any other message)

Without:

[13:27:13] [Server thread/INFO]: Preparing start region for level 0
[13:27:15] [Server thread/INFO]: Preparing spawn area: 4%
.....
[13:27:46] [Server thread/INFO]: Preparing spawn area: 97%
[13:27:46] [Server thread/INFO]: Done (36.246s)! For help, type "help" or "?"

List of mods: https://gist.github.com/DeadSix27/df6ed6b085cd14497e13fcb362883020
Config: https://gist.github.com/DeadSix27/588ac78f945529c407626f9a0d2db50a