`word_break_helper` is a character filter used in Elasticsearch. It defines additional word breaks, including period (.), underscore (_), and parens. These make sense in many cases—//word_break_helper// being split into three words, //wikipedia.org// being split in two, //(unintentionally)poorly(parenthesized)// words being split up.
However, `word_break_helper` also splits up acronyms and initialisms (//U.S., N.A.S.A.,// etc.) which isn't really helpful. There is also a quirk of Elasticsearch that you can configure a character filter with a language analyzer, but it doesn't do anything. So, we have "disabled" `word_break_helper` in some cases when we've unpacked analyzers, including French and Swedish, because it wasn't actually doing anything before unpacking.
In general, `word_break_helper` seems to be a net positive, and should be enabled everywhere, but we need to figure out a way to do smarter handling of acronyms (which we probably don't want to split up) and domain names (which we probably do want to split up).
There is also `word_break_helper_source_text` which is used elsewhere, and includes colons (:). I haven't looked into how it's used and whether it's helpful as currently configured.