Tribe nodes is going to pick one when there is a conflict, e.g. duplicate index name. That's going to be your first problem there. Secondly I do not know if it is possible to create alias in downstream clusters from a tribe node.
You have some minor control over which cluster a tribe will favor via the on_conflict: statement, but then you are stuck to always using that cluster :-). So that does not solve your problem.
The simplest solution I can see is to run a script in each downstream cluster and create aliases mapping the duplicate indices to unique name.
For example 3 downstream clusters that we will call cluster1, cluster2, cluster3 and the set of indices that are duplicate as idx-YYYY.MM.DD
Write script to use curator and create aliases in each cluster.
alias cluster1-idx-YYYY.MM.DD ---> idx-YYYY.MM.DD
alias cluster2-idx-YYYY.MM.DD ---> idx-YYYY.MM.DD
and so on.
Now in your tribe nodes, you can refer to the unique downstream indices via aliases.