superflat presets doesn't work

Some preset doesn't work when creating a custom superflat world

What I expected to happen was...:
I wanted to change vilage size and distance, give the world the ability to spawn strongholds and decoration and more.

What actually happened was...:
It just uses the default preset, but the block selection is intact
If I want to have a stone layer and decorations, only the layer of stone will stay, the decoration preset will be removed.

Steps to Reproduce:
1.  Create New World
2.  More World Options
3.  World Type : Superflat
4.  Customize
5.  Preset
6. Delete all text 
7. Copy and paste this: (this is an example of a custom preset)
minecraft:bedrock,20*minecraft:stone,2*minecraft:dirt,minecraft:grass_block;minecraft:snowy_tundra;village(size=5),stronghold,biome_1,decoration,lava_lake

8. Create World
9. Type /locate stronghold

--> As you can see on 1.png, it doesn't detect any stronghold... if you go mining you won't find ores and the village size doesn't change too.