J'ai corrigé sur LRC des taches et après transfert sur LR elles réapparaissent.

That depends on how you want them in Lightroom. If a smart preview size image is good enough, then you can sync the Lightroom Classic catalog and place such an image in a synced collection. It will then automatically appear in Lightroom. If you want a full size image in Lightroom, then you'll need to export the image from Lightroom Classic and import it in Lightroom.