left two 'UFO' icons are too vague and confusing
Those are from Josh's concept and are probably supposed to resemble the scout/fighter UFO designs.
I like their "alien symbol" look. But of course we can add some lines to make them look less abstract:
And thinking of it, when I look at the Geoscape and what has been proposed so far, I believe it would look best to have uniform silver pins (like Ghostas first) sticking in places, with those symbols on circular/square/triangular colored heads.
P.S.: Something like this.
The "code" being
Pin -> mission / temporal marker
Shade of orange -> alien activity
Triangle -> assault (may include installation attacks)
Kerrblade symbol -> terror site
Again, this is photoshopped.
If you would like to try the models in-game, I'd be glad if someone could make them.