The map and address search run on free, community-maintained open data (OpenStreetMap) plus public US Census address data — no paid provider — so some rural or new addresses may be missing or only approximate. If a lookup misses or lands off-spot, switch on Satellite and drop or drag the pin by hand, or paste raw lat,lng to place it exactly.
This replaces the entire drawn line with a fresh road route — from your start, through every checkpoint in list order, to your finish. Your start, finish, and checkpoints stay where they are; only the line is rebuilt. You can undo this.