As you are aware, with no Catalog backup / DR Package, you will have to reinstall and set up everything from scratch.
I would suggest making sure in the future the customer has a catalog backup, with the DR info sent to an email address.
To answer your question, yes, you can restore the backup data by phase 1 and phase 2 importing the tapes.
You will need to setup and inventory the library, ensure the tapes are NOT in the scratch pool if you set one up (cannot import a tape if it is in scratch).
This TN explains how to import: https://www.veritas.com/support/en_US/article.100017201
It's simple enough, but will take some time depending on how full the tapes are. Phase 1 is fairly quick as it just skips through the tape looking for the backup headers, phase 2 reads the actual data in, so can tape several hours per tape, depending on tape capacity.