This all stems from a delayed connection and the lack of regular service onwards to MEL.

1. You won't likely find too many Mandarin speakers at a domestic connection in the US. If you book itineraries such as this, you should not presume that everybody speaks English.

2. Roaming is in the past. Skype. Even if you can't get free WiFi, paying for WiFi will always be cheaper than paying per minute international roaming.

3. For all the UA-bashing in this forum, it is really good about handling IRROPS which are outside its requirements. Rebooking here was the responsibility of the carrier causing the delay, e.g. CA. UA could have sent you straight back to CA.

The greatest risk here is not simply the tight connections but the circuitous routing onto a less than daily service.