Anubias flower submerse routinely. Of course there is some question if these plants ever really "know" that they are submerse. They don't set seed in my tanks sumberse.
Most tank aquatics do send shoots to the surface or beyond to flower (swords, val, crinums, water lily), or do emense growth before flowering (most stem plants), or only flower normally when grown emerse (Crypts).
But aquarium aquatics are rarely grown for their flowers.