How do you troubleshoot random XSL-FO behavior?

I am generating documents from DITA and for some of my translations I'm
getting a page break after a certain chapter. English doesn't have the issue
and if I diff between English and one of the affected translations, the only
difference I see is text and IDs.

I've broken the problem down into a small FO sample but I feel like I'm on a
wild goose chase as random things seem to affect the break.

If anyone is up for it, here's a pastebin of the XSLFO:
http://pastebin.com/9HqkxKUK

If you search for before break and after break you can see where it's
happening.

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