Old instruments seldom seen, an interesting piece to return back into good working condition, well done sourcing information about this unique piece.
Hopefully you will find strings to bring back to former glory, good luck!
Some research to get her tuned in again.... https://www.ebay.com/b/Autoharp-String-Instrument-Strings/182172/bn_105903939 or https://www.stringsbymail.com/autoharp-strings-508/ will keep a look out for future songs from yourself and Claire.