There is no where for the Agent to set their preferred language if only one language pack is selected in Admin Panel -> Settings -> System.

It never occurred to me when setting up the Admin side that the Agent's dates would be changed because we only had the US language pack installed. I assumed when I was setting the Locale Settings and the Date/Time Format that everyone would use those settings unless they specifically (manually, not by some strange default setting) overrode them. Still find it strange to default to setting locale based on language, especially a language like English. You even have Timezone sitting there which is a much more reliable indicator of Locale.
I feel like this whole thing is a bit complex and I'm finding it difficult to simplify but I'll try:
With only US language installed in osTicket
Admin Panel -> Settings -> System
Locale: Perth, WA
Date/Time Format: Locale Default
Language: US
Agent Panel -> Profile -> Preferences
Time Format: System Default
Preferred Locale: Use Language Preference <--- Would like a "System Default" option here
Web Browser
Preferred Language: GB
Result
Agent's dates show as MM/dd/yy even though their Browser is set to GB. I am assuming this is because the only language pack that is available in osTicket is the US language pack. This overrides the system default of using the Locale Date/Time Format.
With GB language installed in osTicket
Exact same settings except Admin Panel -> Settings -> System -> Language: GB
Result
Now an Agent's dates will show dd/MM/yy. I am assuming it is because the Browser language is able to match the osTicket language and show the correct date.
If we could just have Agent's Locale match the System Locale by default, there would be no need to mess around with installing GB language pack, which as far as I can tell changed nothing except the default date format. Also, the wiki has no page on how to install a language pack, only how to run a translation after you have installed a language pack.
Maybe in Admin Panel -> Settings -> Agents -> General Settings add a "Default Agent Locale" option in case there are people out there who are very happy with the locale being overriden.
Hope that's clear enough. Thanks for your time looking at this, obviously something so nit-picking pales in comparison to the wonders coming with v2 😅