Was Cherubini underappreciated (perhaps "unsung") at the time making him no threat to Beethoven's supremacy?
Cherubini was a major musical figure of the time, almost certainly more influential on the music world than Beethoven during Beethoven's own lifetime. I think Beethoven was influenced by
Lodoïska in particular when going to work on
Leonore. It's a pretty impressive opera. Beethoven also singled out other Cherubini works for praise and personal influence, especially the C minor Requiem.
Cherubini was, for a time, Napoleon's top music guy, though Napoleon thought his music was too complicated. Rossini and Chopin also seem to have thought highly of Cherubini.
I wish I could go to bat very strongly for Cherubini, but though I like his music, with a few exceptions, I'm not really in love with it. But I haven't heard all that much, to be honest. The string quartets are nice, and I like the symphony (which is a fully orchestrated version of one of the quartets). I like two of his operas in particular, but the other (I forget which) was merely okay to me. How much of his stuff has been recorded, all told? There's a lot of duplication in Cherubini releases.