No Errata
Q: Does Flickering Image allow me to push the upgraded fighter after each separate Attack action in an Attack action that targets multiple fighters (e.g. Whirling Club)?
A: Yes. However, the only fighters you can target are those who were adjacent at the start of the action, and your fighter must be in range of each of those fighters to make an Attack action against them. If the fighter is pushed in such a way that they are not able to make an Attack action against any of their remaining targets, no further Attack actions are resolved.