Hello and welcome.
There’s another option you’ll want to set. See my post here: Amazon Glacier Best Practices? - #6 by drwtsn32
I don’t really know how restores would work. You might need to determine which files will need to be downloaded and then change them to a higher tier at least temporarily.
If your local database gets deleted, it should be able to be rebuilt from Duplicati reading all the dlist and dindex files. In some cases Duplicati might decide it needs to read dblock files, which could be pretty painful with archive tier storage.