Here is an example query of how to find log data in Splunk when using this plugin.

index="jenkins*" sourcetype="text:jenkins" source="job/deadmanssnitch%20(DO%20NOT%20DELETE)/5830/console"

The main issue is that the plugin escapes the " " and makes it "%20" but that application in Splunk expects there to be a " " not "%20".

Here is an example search that the Splunk Jenkins application runs

index="jenkins_console" host="platform-engineering-test.jenkins.nonprod.bxt.com" source="job/deadmanssnitch (DO NOT DELETE)/5830/console

It seems like over time that https://www.google.com/search?q=splunk+jenkns+app&rlz=1C1GCEU_enGB935GB935&oq=splunk+jenkns+app&aqs=chrome..69i57j0i13j0i22i30j0i8i13i30l3.3528j0j7&sourceid=chrome&ie=UTF-8 version 2.0.4 has fell out of sync with https://plugins.jenkins.io/splunk-devops/ version 1.9.7.

Thanks