I guess so. That's where mine are planted and they have been growing there for at least five or six leaves, maybe more.

Scattering hellebore seed beneath the tree is the best option.
Maple roots are dense and at the surface. Have you tried digging where you want them to grow? I would recommend scattering organic matter - shredded leaves, mulch, beneath the trees on a regular basis.
If weather becomes dry, you will have to water the plants as the maple roots will suck out all moisture.

I have them under all the trees around here. Tulip poplar, maple, ash, hickory, gum (nissa), redbud, sassafras, and walnut. Doesn't seem to make much difference to them. They all go wild with self seeding all over the area.