Another composer, Ferdinand Hummel, also composed a Piano Concerto in Bb minor, but only a reduction for 2 pianos survived. Both Hummel and Kauffmann are Kiel's students, both fallen into obscurity after death.
...and Kiel was evidently an excellent teacher as well as a fine composer himself.
IMSLP has a few interesting-looking works by Ferdinand Hummel (several chamber works, for example) some of which can be performed as is, I suppose I should add. I should be more selective in my interests, I know. (Fleisher has the full parts for his concert fantasy for harp and orchestra, for which IMSLP just has the harp solo, btw.)
Wikipedia has this article: https://en.wikipedia.org/wiki/Ferdinand_Hummel
How about this charming miniature movement from 'Im Frühling: Lied', No.3, Op.37?
https://www.youtube.com/watch?v=ozUdUneAuRU
It's from this lovely CD: https://www.prestomusic.com/classical/products/9337264--quatuors-pour-trois-instruments
It's pity that only his 'Alleluia' gets the most attention nowadays. I am looking for anyone who has the capability to orchestrate the 2nd piano to full orchestra for his piano concerto. The movements are as follows:
I. Majestatisch
II. Einfach und innig
III. Lebhaft und feurig - Maestoso
Here's his 'Alleluia' (orchestrated):
https://www.youtube.com/watch?v=45Pw83EsBus
...sounds rather like something by Gounod or Massenet!