Thanks for the feedback! I've released a new update.
1. I swapped the numbers of 41 and 61, so covering stones is more expensive.
2. I re-balanced the fights for 53, 97, and 100. The last fights are the hardest for me to balance, so let me know if they still feel off. (Hopefully nerfing 41 made them harder.)
3. I'm planning to add a new post-game tournament eventually, with more variety and difficulty. For now, the intended post-game is to collect all 30 stones. Or start a new file and reach the tournament in 20 battles or less (excluding puzzle battles).