In a binary system of artificially immortal stars, each one orbited by a ring of mirrors, a whole line of Earthlike planets orbits the binary within its habitable zone, from 400 to 800 AUs. While some of the planets won't have an axial tilt (meaning no seasons), most will have the same level of obliquity--19.7 to 26.9 degrees on an undetermined cyclic length. All have the same rotation--just 30 hours. But because of the binary's combined mass, the revolution of the inner boundary planet is 12,000 hours and the revolution of the outer boundary is 21,840 hours.
All the habitable planets are barren, with barely a single microbe in sight, perfect for the process of the latest trend in speculative evolution--seeding. And that's where the issue of "alien sunlight" comes into play. Compared to our sunlight, how much would be "too much" for Earth species, and how much would be "too little"? Too much, and the seedlist would have to be strictly marine, as the ocean waters would protect the lifeforms from the intense radiation. Too little, and the germination of plants would take far longer than back home.
So, generally speaking, with our amount of sunlight in the middle of the spectrum, what are the maximum and minimum amounts of "sunlight" that any Earth species would stand?