"logging event link-status" should create the log event for the buffer to capture and this applies for the entire normal operation of the switch and not only at boot time.
If your buffered log does not capture these messages, maybe the level of logging set for the logging buff. is not enabled to capture these.
'logging buffered 40000 ???????' <--- here
In curious on what you mention about the interface load. Where do you see that? Could you please paste the output of 'show interface xxx' where you see that?
Oscar