checkPlace, checkFiller, verifyConnectivity & verifyGeometry will tell you if you need to redo addfiller, refinePlace and / or routeDesign.
( normally you run refinePlace without gap fillers in place )
If your filler cells are totally benign as far as the routing metals go , you should be fine.
I have to addFiller before the initial routeDesign because my DeCap filler cells have additional M1 geometries inside the typical M1 power rails.
Luckily optDesign -postRoute is smart enough to automatically deleteFiller > optimize > addFiller > routeDesign