Am I at risk of health complications if I just inherit one risk variant for alcohol intolerance?

Yes. Heterozygotes who have just one copy of the slow ALDH2 variant may not experience very severe symptoms straight after drinking alcohol. This means they may still drink alcohol occasionally or may become heavy drinker. Despite the lack of immediate alcohol intolerance symptoms, these individuals still have a 10-fold increased risk of esophageal cancer (for moderate drinkers) or 90-fold increased risk (for heavy drinkers).