If someone has dysphagia but eats enough, will there be any long-term complications?

No. Dysphagia is a symptom. If it is causing weight loss... It becomes a "red flag symptom." if you have dysphagia, though, it should be checked. You can start with your local ent.
Depends. Patients with dysphagia can have aspiration when food or liquids go into the windpipe (trachea) instead of the esophagus. If aspiration is not present, and the person is eating enough calories in spite of the swallowing problems there should be no long term problems.
Depends. Dysphagia risks is aspiration pneumonia & if nutrition can be maintained with adequate intake it helps but does not prevent the aspiration or reverse the condition.