I am going to rename the suffix for the local tiered objects to also use .wtobj. That makes it more cohesive to talk about WiredTiger objects as part of a tiered table and leads to less confusion for someone seeing a file name in a directory. Tables ending in .wt imply a single complete btree.
It also eliminates name collisions if someone were to create a local table with the same name as one of the objects as they'd have different suffixes and different on-disk file system names.