Warning, I'm more of a powershell guy than Perl. However, checkout the "Initialize or Update Storage Virtual Machine SnapMirror" command. They have an example in there on how to post to the log, and just use the info flag instead of warning.
my $wfa_util = WFAUtil->new(); $wfa_util->sendLog('INFO', 'Connecting to cluster: ' . $DestinationCluster);
You can also set the "Advanced" option on the workflow command to continue at the next step in the workflow on an error. This way you can throw the Error to the WFA screen, and the workflow will continue. Before this feature was available I used a command to throw the error at the end of the workflow and made the text say WARNING. So I think you have multiple options for this. Take a look at the advanced tab. You may want to ensure that your checks are in there own command, so that you can stop the workflow on a legitimate error as well.