Parse and show all errors from apache error log specific to user

Cpanel -> Metrics -> Errors shows all entries based on this line of code:

USERNAME=cptest; { grep -Ei "(/home/$USERNAME/)" `readlink /usr/local/apache/error_log` && grep -Ei "($USERNAME)" /usr/local/apache/logs/suexec_log ;}  | tail -n 300

However, this misses some important messages like:

[Wed Jun 02 14:08:29.797254 2021] [lsapi:error] [pid 2177807:tid 23251490592512] [client X.X.X.X:50570] [host www.XXX.si] Error on sending request(GET /manager/?blabla=blabla HTTP/1.1); uri(/index.php?get=500.shtml) content-length(0): ReceiveAckHdr: timeout 300 is exceeded, referer: https://www.XXX.si/manager/?mod=blabla

So the feature request is simple. Include all error messages related to websites (vhosts) of the account hosted, not just he ones that contain username.