I doubt using a strong helper squad is enough to compensate for your squads currently, especially since RNG can require each squad to be equally strong. ?-4 will be even harder for you.

For now focus on farming Manyus to upgrade, just keep farming 1-3 or 2-1, and the bonus stage that you sometimes discover from it. You still have much time so don't worry about the event for now, no point wasting stamina on stages you cannot clear anyway.

(Also, the knights in the ally's helper squad you use gets nerfed to the max level of your units, so another incentive to farm & upgrade your girls)