I thought of two ways that may solve or reduce this problem:

1. give a bonus for every guess, instead of punishing a wrong guess. Currently it is a disadvantage to guess even if there are only two squares where a frog may be: the player who guesses first can earn 5 or loose 8 points, with probability 1/2 each, so the expected win is negative. It should be positive instead.

2. Don't allow to shoot at a square X if all squares adjacent to X are shot or guessed or adjacent to a shot square that shows a number equal to the guessed or killed frogs around it. This means that there cannot be further unknown frogs around, and shooting X gives no information (except if there is a frog on X that will be killed).

BTW I can't see a reason not to display the wrongly guessed squares on the board (e.g. by a '-' sign), they are in the move list anyway.

It might also be good to increase the number of frogs. 9 I find a bit few...