To better surface the now always present result at the top of the suggestion, that let's you add an undocumented parameter, we decided to set change the style of the descriptive text underneath Unknown field by putting it into parenthesis and formatting it italic.
Follow up to T285940: Template parameter search: partial match blocks adding undocumented parameter
Note: While it might be possible to use https://translatewiki.net/wiki/MediaWiki:parentheses and combine it with the existing message, I feel it's better to add the brackets directly to the existing message. This way translators can change it easier. The same is done with https://translatewiki.net/wiki/MediaWiki:redirectedfrom.
We just need to make sure the message https://translatewiki.net/wiki/MediaWiki:visualeditor-parameter-search-unknown is not used anywhere else.
Change 703612 had a related patch set uploaded (by Svantje Lilienthal; author: Svantje Lilienthal):
[mediawiki/extensions/VisualEditor@master] Change style for adding an "Unknown field" in the parameter search
Change 703612 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@master] Change style for adding an "Unknown field" in the parameter search