Why should these communities pay back. They've already paid in with their loss of generational wealth, lack of education, lack of access to sufficient housing and healthcare. I don't know, loans don't feel right.
If your plan is to have this be paid by taxes, then these communities will already be paying for their own reparations through having to pay tax. You may get a slightly better from corporate tax, but you'll still have the descendants of those enslaved during the trans-atlantic slave trade (some who will also be descendants of slave owners) paying for their own reparations.
If it's a one-off personal payment, then it's a one and done thing and likely to be uneffective in changing anything. A system where the money is properly invested by the community, loaned and return, means not only is not all the money gone out at once, but it can be reused by members of the community over and over - it's paying it forward to the next generation just like wealthy families do all the time. It's really the closet I've heard of being able to recreate generational wealth because whatever number we can get the government to part with, dividing it up among everyone isn't going to get families there.
Yes, there is administration involved, but I'm not sure why I would trust the government that for so long enabled and fought for these injustices to be less corrupt or have less administration involved. Admin is always going to be involved - the question is who is going to be responsible for it. That I think is going to be a larger complication here.
If we want a realistic idea of how to get political support for reparation and how to manage it, we should look to the groups with the most similarities which is going to be Indigenous groups devastated by European colonization - and the problems between nations recognized and those that aren't with this is something to consider, but coming from that perspective and perspective of not thinking an individualistic solution can solve a social problem or that we can get the social support to get an amount big enough that it would make a difference once it's divided up to everyone, I stand by the choices of those nations who've since been able to loan out far more than the original amounts. It's not justice, but it's a way to reform social systems.