Good evening Matthew and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
Actually, the labels for the fields are not using our language files by default.
But, the good news is that you can change those labels to your liking by going to Events -> Settings -> Filters.
From there, click on the downward arrow on the Event Category section and you should be able to use the label of your choosing.
Let me know if that helps.
Have a great day!
Geoff B.