I see this has already been answered, but I’ll post what I was typing out anyway.
It’s not enough to just provide your auth token if you want to fetch the details for yourself (even though the JWT decodes to identify you). You have to use /user like you would for fetching anyone else, e.g.:
curl --header 'accept: application/json' --header 'authorization: Bearer xyzyzyz' --location https://lemmy.world/api/v3/user?username=okelote360 | jq .
You can’t. resolve_object in the API needs a full URL - something you could also put in a browser to uniquely identify an object - a user, community, post, or comment, but not a modlog entry.
You’ll have to get the mods / admin at blahaj to flip the ban again.
Other instances have recorded that particular unban, so it’s possible that - at the time it was sent, lemmy.nz rejected it because the community didn’t have any local subscribers. So, considering the activity, it would be a lemmy bug. Maybe not though, maybe lemmy.nz was just down at the time. Anyway, it’s showing 1 local subscriber now, so assuming that’s a different account, another attempt should be acknowledged.