The config log is the raw low level values in the config tables, but when reading the logs often this isn't that useful. I think a few low hanging fruit could make this much better:

• First always show the raw value even if any of the follow conditions are met
• If the value looks like a timestamp then convert it a human readable string
• If the value belongs to an admin tree setting eg a dropdown, then have that admin setting return the human readable string for the number. This would require the admin setting class to have an opt in method for this which we'd implement in all the critical core classes but 3rd party ones don't need to have it.
• For those settings which intentionally don't have an admin tree settings eg CFG->siteadmin then have an equivalent hook. In this specific case mapping the list of user ids to human readable user names / links 
• These functions would take both the old and new value so they could also do things like a nice html diff in the case of things like large html config which only has 1 line of change and its near impossible to see this currently.