Yes, you can. Go to Special:Allmessages in your wiki, and type User-identity-box-group in Filter by prefix:. The page displays the default message text for each individual user rights (local and global). There, you can edit those MediaWiki messages.
A few of them (e.g. vanguard, global discussions moderator, etc.) can't be edited because they're not whitelisted, so you'll need to contact Fandom Staff if you want to make changes of those.