Bush foraging rate is just fine for me. Increasing it will just speed up the game and throw civ balances off, imo; including faster age-up times due to faster berry collection rates, etc.
If the gameplay is too slow for you and you want a faster game, in general, you can play on a faster speed. But if the current “Fast” speed option isn’t fast enough and you want even faster speed options, like me, please like or contribute to my thread here:
My suggestion is mainly for single-player and unranked matches. But there is brief discussion on how it might be cool to have faster speeds available in ranked games someday, too.
That said, I like the current berry-collection rate, as is, relative to other collection rates.