Edit: Don't mind me for now.
Edit2: Mind me now. Your properties for the script don't transfer over to papyrus fragments.
That's really interesting to know. I never would've guessed.

If the *only* thing your script does is start the scene then you can do that entirely in the fragment. You just need to add the scene as a property and then call start(). If there's more to your script than that, I can think of a few other ways of starting the scene...
And yeah, that's the only thing the script does. So, I've tried doing it in the fragment instead, like this:
Scene Property Stage12 Auto
Stage12.Start()
But now I get this error:
Starting 1 compile threads for 1 files...
Compiling "QF_danMainQuest1_01003F83"...
c:\program files\steam\steamapps\common\skyrim\Data\Scripts\Source\temp\QF_danMainQuest1_01003F83.psc(33,6): no viable alternative at input 'Property'
c:\program files\steam\steamapps\common\skyrim\Data\Scripts\Source\temp\QF_danMainQuest1_01003F83.psc(34,7): no viable alternative at input '.'
No output generated for QF_danMainQuest1_01003F83, compilation failed.
Batch compile of 1 files finished. 0 succeeded, 1 failed.
Failed on QF_danMainQuest1_01003F83