-snip-
Or is this a still unsolved bug ? Any help appreciated. Thanks
If you really want to import those transactions (with that bug), since it's non-descriptor, you can import any of the outbound txn's outputs' address as watching-only.
The outgoing txn's output will be included to your "Watching-only" funds, spending the previous inbound transaction's output.
But the best workaround if the goal is to spend a pruned output is to import only the pruned transactions that aren't spent yet, just do not import the spent ones.
This doesn't solve the linked issue's OP though.