So, the entire "global/resources" folder was excluded for some reason (hence it not getting returned in searches). However, even after adding it back in, I am faced with the same issue. I also can't find these specific resource strings in these files.
I am using the following attributes in my properties file for the widget in question:
[EditingComponent(PageSelector.IDENTIFIER, Order = 100)]
[EditingComponentProperty(nameof(PageSelectorProperties.Label), "My Label")]
Maybe this has changed in V13?