Currently, the content of the english version of apihelp-pagetriagelist-param-non_autoconfirmed_users is "Whether to show only pages created by non auto confirmed users."
There shouldn't be a space in "auto confirmed", just as there isn't one in apihelp-pagetriagelist-param-learners.
Change 515357 had a related patch set uploaded (by DannyS712; owner: DannyS712):
[mediawiki/extensions/PageTriage@master] Remove extra space in apihelp-pagetriagelist-param-non_autoconfirmed_users
Change 515357 merged by jenkins-bot:
[mediawiki/extensions/PageTriage@master] Remove extra space in apihelp-pagetriagelist-param-non_autoconfirmed_users