The 60 minute - one engine - still air - rule is pretty much universal. I've seen it at several airlines in the US, Europe, Canada and Asia.
Although I say it's universal, there are variations. For example, one airline that I am familiar with states the following....
"....take off alternate of 424 miles for the B777...380 miles for the Airbus A321...437 miles for the B767..."
Interestingly, this is about 1 hours flying time on one engine.
Could your company's FOM / OPS Specs require a lesser distance? Absolutlely! An FOM can always - and quite easily - be more stringent than the appropriate countries regulations. But, you are giving up something in dispatch reliability.
I'd be interested to know what the "Audit" recommended about enroute diversion airports. Do they recommend the same 30 minute criteria? That could make trans-ocean, or international operations difficult. And, it could certainly affect domestic operations.
That 30 minute requirement - depending on your drift-down stratagy - could put you in a difficult position if traversing 114 degrees West.