I'm not sure we actually need to use the plural macro here, but this is definitely a reasonable direction in which to err since the tools available to localizers mean it's practically impossible for them to decide to use the plural macro if we haven't done so initially.  (If they were manually editing the file it'd be fine, of course.)

Which is to say, I agree with what you're doing here because I could see a localizer arguing for this, but I also am acknowledging this is weird.  (No doubt to you, too.)