If I understand you, the data is being ingested and is going to the index (network?) you've defined in the input stanza. The data is also being source typed: the index contains source types: barracuda:system, barracuda:web, and barracuda:waf. Is that correct?
If the above is correct, it means that the regex matches are successful at a base level.
Looking a bit deeper at the Add-on's props.conf for the "barracuda:waf" source type, there are a number of additional fields:
[barracuda_waf_extractions_1]
REGEX = (WF)\s([A-Z]{4})\s(.+?)\s(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\s(\d+)\s(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\s(\d+)\s(DENY|LOG|WARNING)\s(NONE|LOCKED)\s\[.+?\]\s([A-Z]+)\s(.+?)\s(.+?)\s(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\s(\d+)
FORMAT = log_category::$1 vendor_severity::$2 signature::$3 src_ip::$4 src_port::$5 dest_ip::$6 dest_port::$7 vendor_action::$8 vendor_follow_up_action::$9 http_method::$10 url::$11 vendor_protocol::$12 proxy_ip::$13 proxy_port::$14
They were also kind enough to provide a data sample as a reference. You can find the example in: /Splunk_TA_barracuda_waf_adc/samples/barracuda_waf.sample
If you search for the source type "barracuda:waf" in your index over the recent time period when data has been ingested, and the data populates on the Search view, do you see any of those fields on the left side list of fields? The ones I expect to be very common are "dest_ip", "dest_port", "src_ip", and "src_port". I cannot say how often to expect any other fields.
Take a look at the sample data for that source type. Do there appear to be significant differences if you compare it to one of your events that's being ingested "live"?
When I've seen mismatched Add-on parsing for a given data source in the past, it is usually down to product version differences. The Add-on might have been written for an earlier or later version of the barracuda product than the one you're using. As the Add-on doesn't contain any version info, you can always contact the writer for clarification as well. The last line of the readme file has an address to contact.
If those fields are extracting properly, then there might not be any problem. You'd have to find a field that should've extracted from the source data that failed to, and review the regexes designed to capture that field. Grab an event from your index, clean it up a bit, grab the regex strings from the Add-ons, find an on-line regex tester, and do some quick checks! Note: I did this using the regex above with the sample data on regex101, and the resulting groupings were a match for the listed field values.
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