Placing the adverb directly before the verb should be marked as correct.
And preferable, honestly.
Celeriter is also ok i think but it's marked as wrong
"Ignes pontes celeriter delent" is accepted now.
(And thank goodness adverbs are not declined.)
That would have destroyed Roman civilization earlier.
so ignes and pontes are both nominative and accusative right? Is there any way other than context to distinguish what is destroying what?
Context is a big one, but word order can help. Often times, the nominative will appear at the beginning of the sentence.
These bridges are obviously not fireproof.
Wooden bridges plus flying parrots on fire.
= Ignes rapide pontes delent.