Similar theme - string concerto (concerto for stringed instrument and orchestra (string, small or full)) wish-list for works with available digitized score and/or parts to aid in performance and/or realization, time period ca. 1840-1910 give or take, etc., commercially unrecorded, etc. ...
My suggestions to start with:
*Friedrich Hegar's cello concerto in C minor (https://imslp.org/wiki/Cello_Concerto,_Op.44_(Hegar,_Friedrich)) op.44 (actually probably composed 1919, but seems to be thoroughly Romantic. Full score available.)
*Fritz Kauffmann's cello concerto in G minor (https://imslp.org/wiki/Cello_Concerto,_Op.29_(Kauffmann,_Fritz)) op.29 published 1899 (performed by Julius Klengel in 1902. Again, full score available).
*Hermann Zilcher's 2nd violin concerto in manuscript full score (https://opacplus.bsb-muenchen.de/title/BV045296272). (I don't think this has been recorded. IMSLP has the reduction.)
Here's Zilcher's concerto in an ancient and very dim recording:
https://www.youtube.com/watch?v=1ytOn6v8PHE
yes, that was one of our uploads, I remember. There's still good cause to create a modern (if perhaps copyright restricted because of the dates) performing edition to encourage something better, perhaps? Dunno.. but it may be too recent, too...
Also: Auguste Franchomme Cello Concerto no.1 in C minor parts (https://gallica.bnf.fr/ark:/12148/btv1b52502935x) (Op.33). (Reduction is at IMSLP. There is a live recording @ YouTube.)
On the basis of the first concertino,
Kalliwoda's violin concertino no.2 (https://imslp.org/wiki/Violin_Concertino_No.2,_Op.30_(Kalliwoda,_Johann_Wenzel)) (parts).