Yes, I have a thought.
We need to start teaching umpire to read the FIELDERS for chase situations instead of the "ball." If U3 has focused on F6 (eyes on the field), she would had seen how the play was developing and that no chase was required (and then moved to a position at second in case the ball was dropped). Trying to "guess the play by reading the ball" with her eyes skyward leads to bad reads.
This is akin to PU reading the catcher of fly balls around the plate. If PU "looks up," then there is a danger of being run over by the catcher.
I very much teach umpires to read players and not the ball for all chase situations. The only exception is when there is a question of fair/foul on a home run, as you then have to shift your focus to when the ball clears the fence. This also helps to decide who's chase area the ball is in by watching the fielder go into the chase area.
This also helps PU who doesn't work much 3 umpire because now their eyes are focused on the field. Their partners are now within the visual range. I tell people the best way to develop this skill is by working slow pitch, where there are more opportunities for fly balls.
If you want, we can discuss this theory more this summer, maybe in the mid-west, over a plate of ribs (and yes, I will be there the entire week this time
).
Therefore, as to your particular play, U3 should be moving towards second by being mindful of F6 catching the ball and then not being in any throwing lane when she passes F6 (maybe a "deeper" path is optional).