Welcome! Never heard of the composer, so I took a listen. Very interesting! Wikipedia says she's a link between the classical and romantic composers, and I can hear it:
Is this IMSLP version not correct? The first few measures look exactly right:
https://imslp.org/wiki/Cours_complet_pour_l'enseignement_du_forte_piano_(Montgeroult%2C_H%C3%A9l%C3%A8ne)
The link titled "Studies 71-114", page 98 of the PDF (page 96 if you are going by the printed page numbers). It's not listed as "112b" but it sits between 112 and 113.