Do other players replenish their traded cards after a trading phase in Bohnanza?
To the best of my knowledge, there is no "minimum hand size" rule in Bohnanza.

The active player draws three cards at the end of his round, but it's perfectly possible to start your round with no cards at all in hand!  As demonstrated by this line in the "1. Plant bean cards" section of the rulebook:


  If the active player has no cards in his hand, he omits this step.


So, no, you don't draw to replace cards you used in trades, at least not in any variant of Bohnanza I'm familiar with.