Yes this command will show me the inputs that Splunk is currently monitoring. It does not indicate if one of these monitored inputs is no longer being indexed for any given reason.
Rather than going for splunkd.log you can search in splunk metadata command. You wont be finding any indication in the splunkd.log if is has been stopped for monitoring because splunk will keep on monitoring but doesn't actually read anything unless it has changed state.
|metadata type=sources index=Index_Name|where source like '%part_of_Source%'
Of course you wont be able to find if there are many hosts having the same source names.