I thought so too!
Musescore did that automatically, and any time I tried to change it, it just inputted the eighth triplet on its own (???) I guess maybe that measure is corrupted in the file and somehow the program didn't catch it? I'll try to do somethin' about it, again, at some point lol
Thanks for pointing that out to me, confirming that suspicion lol!
But I suppose it's easy for me with brass quintet music because I was a trumpet player for the better part of 11 years. I understand intimately, the timbre, range, and capabilities of a trumpet, and the other instruments in the brass family as well. Trumpet came naturally to me, as well, once I picked it up. LOVE me some brass ❤️