Create tickets out of keywords in automation rule is not fuzzy/reliable enough - how to harden?

[Bernd Gurn]

We have set up several automation rules in JSM (Jira Service Management) checking for keywords in the subject of an incoming Email. When rules matches depending on the right combination of keywords (like "ACME-Service" plus "Reference-ID" or "ACME-Service" plus "Incident-High") the issue is created as service request or as incident (and with prio high). Works in general but needs some optimization. We don´t use the "Match Case" checkbox for the comparison of the values in the  subject and had hoped that the system could also intercept inaccurate information or spelling errors in the keywords. Unfortunately it isn´t. Don´t know why.

Any ideas out there to make the recognition of keywords more reliable?

We use the "Issue fields condition" field and put the list of keywords like above examples in the "Value" field. As mentioned "Match Case" is not checkmarked. 

PS: I looked for a way to use RegEx but i couldn´t find a applicable way for us in that kind of rule. Which type of i have to use and where´s documentation to find.