I don't think this is a Kibana issue, more of the external source (if it doesn't work from one day to the next). Did you consider using emoticons in the painless script? there is no good traffic light emoticon for your use case, but I'm pretty sure you find something that would match
Apache, Apache Lucene, Apache Hadoop, Hadoop, HDFS and the yellow elephant
logo are trademarks of the
Apache Software Foundation
in the United States and/or other countries.