For level 3 security the tooltip shown is:

The first paragraph (which is the one needs an update) in EN:

The senders identity was certified by several trusted people.

This ignores that the level 3 is reached by one signature of a fully trusted certificate, too. Which is the more common occurrence nowadays.

I propose to change the text to:

The senders identity was certified by at least one fully trusted or several marginally trusted people.

Additional info (I don't think we need to mention it in the tooltip): if the fully trusted one was certified by an ultimately trusted key (one hop only), that would be level 4