Translation:De warme maaltijd was gearriveerd.
How do you know when to use "was" vs "had" in this tense?
At the end of this page there is a little section on "hebben" vs. "zijn" as auxiliary verbs for the perfect aspect. While that explanation is for the present perfect, the same is true for past perfect (like in this sentence).
Dank je wel!
Why is het warme maal not correct?
I think it should be accepted, probably it's just a missing translation. Have you reported it?