Congratulations on completing the game! It's a pretty challenging one—after all, it's heavily inspired by Touhou—and it looks like you managed to figure out the patterns.
I'm really glad to hear you didn't run into any further problems with the downloadable version.
As for the web version, weird browser-specific bugs are one of the main reasons I usually recommend the downloadable release. Both versions share the same game logic, so it's difficult for me to tell exactly what happened in your case, especially since I haven't been able to reproduce it myself.
That said, I do plan to release a small update focused on improving the browser experience, particularly by optimizing some particle effects and reducing lag.
Thanks again for taking the time to play the game and share your feedback. It really means a lot to me.