Is "The children are afraid of going to the forest." acceptable?
yes.
Why isnt "...afraid of walking to the forest." Acceptable?
Well, although this would be literary מְפַחֲדִים מִלָּלֶ֫כֶת, it is better to leave out the מן.
I wrote: "The children are afraid to walk in the forest" and it was marked incorrect. That's it for me with this app for today. I have no more patience for its inadequacies...
Oh I just realized I should have said "to the forest". Okay my bad...