As a general rule, the chemical compounds unique in the "tea" are not taken up whole by the plant leaves. Hot peppers added to the
compost tea may leave
enough capsicum on the leaves to deter
rabbits and other mammals from nibbling on them, but the capsicum is not taken up by the plant. What is taken up by leaves are fragments of molecules, things that are small enough to be transported through the cell walls of the plant. So while sprays of calcium can be beneficial to
tomato plants, because calcium can be directly taken up by blossoms leaves and young
fruit, the glycosides in digitalis are huge molecules that just won't fit through the cell wall. They will most likely be broken down by the fungal and bacterial cells that are living on the leaves.
That said, I would not go spraying digitalis tea today and harvest things for my salad tomorrow. Poisons may not wash off with a quick rinse, and it may take several days for them to decompose.