If an effect lets you need less cards for a straight flush, you should then need less cards for a straight flush.
You can reduce the number of cards you need for a straight flush by decreasing both the cards you need for a flush (plastic brick) and the cards you need for a straight (snakes). In effect, the cards needed for a straight flush is the greater of the two: cards needed for a straight, and cards needed for a flush. I agree this could be signaled to the player better. Thanks for playing and for the kind words!