Hm, possible; but then I've got a second provider just for this, which seems weird.
Also, the actual situation is (of course :^ ) more complicated: This is in a TF environment where I'm managing resources in multiple AWS accounts, using Terrascript to generate the config for them, and each AWS account already has its own provider... So now I'd need two for each account, one for just the CloudTrail trail. Which, again, is doable, it just seems weird.
Thinking about this some more, part of what I think I was trying to figure out is if this is a Terraform bug; but I think it isn't, because I get similar (if weird) results with the AWS CLI, where `aws cloudtrail describe-trails` shows my trail, but `aws cloudtrail describe-trails --trail-name-list Default` doesn't, unless I add `--region us-west-1`. None of that makes any sense to me, but given that it's what AWS is doing, I'm not sure what else Terraform can do about it. :^p
Thanks for the suggestion! That may be the only way out other than re-creating the trail.