Subject should be changed to User for a simple reason. The term Subject is also used in the contact form and email templates as a label for the topic of the message. Obviously when you have another language you can't use "Subject". The problem is, you can't always translate "Subject" to a term that makes sense in both contact form/email templates and in the Recent Spam Cleaning log.
To give you an example, "Subject" in the sense of a topic of a message is called "Betreff" in german. However it absolutely doesn't make sense to use the same term in the Recent Spam Cleaning log for the user. You can translate Subject to "Subjekt". Then it would make sense in the Recent Spam Cleaning log, but not in the contact form and email templates. So please use the "user" phrase in the Recent Spam Cleaning log.