Mozart's arrangements of J.C. Bach's keyboard sonatas for piano, K.107, are charming works that bridge the transition from galant to Classical style. Their musical distinctiveness comes from their graceful melodies and clear contrapuntal elements, adapted from Bach's originals.
Maintaining a clean and precise articulation, along with a balanced dynamic range, is essential for capturing the elegance of these works.
3 Piano Concertos after JC Bach (K.107) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
3 Piano Concertos after JC Bach (K.107) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.