Welcome to NB!
I like both the names you’re thinking and both match Flora. I wonder though if Wells is easier to say or less staccato than Otto with a D two syllable last name?
I think a “slow” name works with a “harsh” D last. For me, fluency with the last name is more important than a “perfect” match with Flora.
Other names that might work:
Cyrus nn Cy
Otis
Sky(e)
Rufus
Brooks
Silas
Raphael
Magnus
Sterling
Lachlan
Joshua
Ronan/ Ronin
Alistair
Oscar
Tobias
Julian nn Jules (but will likely cancel out June)
Ambrose
Emmett
Wesley
Sullivan
Sebastian (Seb, Bash)
Hoping something hits the right note! 