On wikis (e.g. fiwiki, ruwiki) where is the "flagged revisions" extension, there should be something like "mw-fr-reviewlink flaggedrevs-unreviewed" message on the legend table.
The legend box on the Recent Changes page does not include an explanation for "unchecked page" and "pending edits". These should be added there.
It's been requested for example here: https://fi.wikipedia.org/wiki/Keskustelu_j%C3%A4rjestelm%C3%A4viestist%C3%A4:Recentchangestext#Selitteet_pois