"They remember their grandfather."

Translation: Mereka mengenang kakek mereka.

[donny309620]

Is "Mereka mengingat kakek mereka" acceptable?

[Jspharmando]

Mengingat and mengenang are different in Bahasa.

Mengingat has closer meaning to "to remember (someone)"; "to think about" ; "to view (with mind)"

Mengingatkan has closer meaning to "to remind (somebody)"

Mengenang has closer meaning to "to reminisce"; "(always) to revive in memory"; "to imagine"

[Ms.Fixer]

Yes, "mengingat" is accepted (as of Oct 2021). ==> screenshot https://imgur.com/kTuSjYI

The difference between "mengingat" and "mengenang" is already explained by @Jspharmando. And "mereka mengingat kakek mereka" is one of the interpretations of "to remember" in English.