"Then the risks are more and more important."
Translation:Les risques sont alors de plus en plus importants.
Because "important/e/s" is an adjective that needs to agree with what it is describing. "Les risques" are masculine plural, so the corresponding adjective must be too ie. it must be "importants". If it were just one risk that would be "le risque est alors de plus en plus important" [no "s"].
Thank you! This is a consistent problem, that important is a much broader word in French than in English, but DL does not recognize the difference. I can only conclude that whoever or whatever constructs the sentences and translations must be French. Yes, here you could also say "extensive," but definitely not "important."
Ainsi, les risques sont de plus en plus importants. This was the correct answer given by Duolingo for me, not as above. I wrote exactly this but substituted "Puis" for "Ainsi". Why? It would be very helpful when you reply to a query if you add the person's tag as it is often unclear which comment is being addressed. Thanks.