Hey, hope you are doing fine.
The default defined alarms will change it's language when you change vSphere client's language since they have a translated equivalent hardcoded.
For custom alarms they Won't change language, since it's a custom string
I think it'l be easy to find.
let's say you have defined an alarm "test alarm" with your vsphere client in english and then you translate to spanish. it will remain "test alarm".
Hope this works