This is awesome! I'll add one more technique for you, which might be a bit more useful on a 5x5 board:
Breaking Combos - Instead of capturing a combo, place a low value in the corner. By not capturing, you take away their ability to recapture, forcing them to defend the combo or risk losing it.
The bots can be a little greedy, I wanna try to make another bot that plays a bit more analytical at some point.