Page break can occur between spell header and description.
See attached pdf:
page 4 and 5: Summon Monster I
Even with your pcg I'm unable to get the issue duplicated. I even made a dummy long spell, and it took the entire spell name and text and placed it on the next page.
Which export did you use?
Disregard, it's the old fantasy set up.
This one is being a bit of a beast. Have you tried the Condensed Spell Display? That actually works as you are asking.
As you can see with this attachment, the Condensed Spell Display is working as you requested. I'm not sure I can alter the main fantasy without major work. Though, it's too late to change things drastically at this point.
No further feedback from user. Any improvements in Condensed won't be ported till it's stable and complete.