What kind of trouble can arise from entering the wrong HS code in cross-border e-commerce?

A while back, when I was handling cross-border DDP small parcels sent to U.S. customers, the biggest headache wasn't the workload, but a batch of accessories that were held up for additional documentation during customs clearance because the HS code was too generic, leading the customer to think the logistics provider had lost the package. If you just rely on guesswork based on experience, it's…