Big Bass Splash bonus timing is not fixed
96.71% is the long-run return the game is designed to pay back, and it says nothing about one session. How often the Free Spins round arrives cannot be known in advance, because each spin is a separate random result. Two sessions with the same RTP can end with very different balances, so the return describes many spins taken together, not any single run of play.
96.50% to 96.52% is the RTP range of the other series versions, and the version running in this lobby is shown only in the game rules. Check that page before you assume a figure from one version applies to another.
x5,000 is the highest win the game can pay, counted as a multiple of the bet, and it is reached very rarely. High volatility means wins arrive in uneven bursts, so the ceiling says nothing about how any single session will go. Treat it as a fact about the maths, not a target.