I did in fact took a look at this for you but it seems that view is forcing you to use an AND condition.
The ideal way to debug this is to check with each field starting with 1 then 2 fields then gradually moving up the amount of fields in the search to see where it stops.
It wouldn't be possible to make all the replies private as private responses are ONLY for when providing credentials, Database dumps and Plugins or themes.
Also I would be contacting the relevant personnel to get some more information on this "Your custom field filters are using an internal "OR" kind of relationship, and dependant parametric search for those filters needs "AND" relationships." means