I had same problem of identification with 4 old cards some months ago.
Same period and type.
My only personal solution is to:
Collect all cards of Museums who sell, give permission after accreditation.
Collect original cards and or Fac Similés.
Collect Exposition or documented Catalogues.
Scans ALL this cards, card by card.
Reworks all this scanned cards or numeric pictures via Photoshop.
Print all this stuff on files in real scale. A back per deck.
And.... finaly look and memorize
I passed step 1 in three years time (I have targeted Tarot de Marseille I and II type only plus some mandatory Historical Decks).
But work is never finish of course...
Now I am starting to reworks all this scanned cards or numeric pictures via Photoshop.
Before printing them.
In fact I already reworked and printed some of them and estimate that 50 to 60 decks is a reasonnable figure to finish the job. Tarot de Marseille I & II only.
So,... be patient and call me back in 2/3 years ha ! ha!!
But I am also OK about back design to be not enough to identify: It is rather a period that it can identify rather than a precise cardmaker. Unless exception may be.