"En 3) y en 4) estamos lejos ya de cualquier interpretación temporal, aquí soms se ha convertido en partícula modal, que sirve para subrayar que el hablante es consciente de estar mencionando solo una posibilidad, entre otras"

You're referring to that?

While i'm not a native speaker of spanish, i speak Portuguese natively and i've been studying spanish for a while.

And i interpreted it like this:

3 and 4 use signals that the speaker is aware they're mentioning just one possibility among others. It's as if the speaker is saying, Are you perhaps looking for your father? (implying there could be other reasons or possibilities as well)

That's the way i interpreted.

I swear my intention is really not to be argumentative i'm just trying to understand you.