DLP RegEx Prefix/Suffix or Look Ahead/Look Behind

I've scoured our forum resources as well as the Symantec KBs and documentation. I understand the the following are recommended to improve regex/regular expression performance:

• Look Ahead: (?=(?:[^-\w])|$)
• Look Behind: (?<=(^|(?:[^)+\d][^-\w+]))) and (?<=(^|(?:[^)+\d][^-\w+])|\t))

Here are some of the KBs and forum posts I have seen:

• https://support.symantec.com/en_US/article.TECH222152.html
• https://support.symantec.com/en_US/article.TECH219204.html
• https://www.symantec.com/connect/forums/expression-prefixsuffix

In Symantec's own KB (TECH222152) above, they recommed using PCRE compatible regex syntax. However, as far as I know, DLP uses Java. What's going on here?

Also, the recommended Look Behind seems to always "error out" using any of the regex tools, such as regexr.com or regex101.com. I always get a "lookbehind has to be fixed width" or a "positive lookbehind not supported in this flavor of regex."

Anyone have insights?

Thanks!

Nick