Changing text on event card: “SOLD”

I know this is likely an odd request but most of my events are currently free, meaning cost is $0. The event cards states at the bottom the number of registered sign ups as X “SOLD”. For the time being, at least until events actually have a fee, I would like this to say X “Attending”.

I searched template files but have not found where this can be changed. If possible, could you point me in the right direction on which file(s) to edit?