Not sure if you're still checking this post or not, but I looked at your stage 5 and 6 replays. Here are my pointers:
-You didn't need to bomb on the fairy wave right before Sakuya, if you minimize your movement you'll see a path open up in the blue bullets.
-Like another user pointed out, you're "panic bombing" too much.
-With Sakuya's Misdirection spell card, try not to defeat her so quickly. This will reduce the upcoming bullet spam and may save you a bomb.
-Since you're using Marisa A, you can literally power through Remilia's Star of David, Scarlet Netherworld, and Curve of Vlad Tepes spell cards. Focus your fire on Remilia and you'll find that you can take her down very quickly.
Good luck!