hrm. the Jadin brothers wrote keyboard (as in, playable by harpsichord as well?...
not to be confused with Poulenc

) concertos, but I guess they were more keyboard than piano concertos... (on the Classical side of this forum's lines, also, those, true. ) Still, Hyacinthe Jadin's concerto no.1 dates from 1796-7, and Louis-E. Jadin's concerto no.4 from 1810. Hrm. Then again, Boieldieu's in F is estimated to date from 1792, leaving those in the dust
anyway... and is for fortepiano, not harpsichord? (Not everyone had made that step even at that late date, even though Mozart had long before...) Interesting...