I'll fix all those and mark them as common formations. Back when the Cantodict was newish (those entries are from 2006 so they are quite old), I was using a computer program to segment common formations. The problem is that if the pronunciation for one of the compound words in the common formation was wrong, it would could propagate into the common formations. There is nothing special: that's what you're seeing.Quote
Berrjod
[www.cantonese.sheik.co.uk]
This entry gives 調查 the reading diu6 caa4, which is expected considering the meaning of "investigate" on the character page of 調, which is associated with this reading. The word page for 調查 mentions that it is often pronounced tiu4 caa4, and calls this reading incorrect. However, it seems most of the compounds containing 調查 use the latter reading: [www.cantonese.sheik.co.uk]
Are the readings interchangeable when 調查 is used on its own, as well as when it appears in a compound?
-Tony