Congratulations, hard in two tries is crazy! The difference is only numbers, but then hard and easy are night and day.
Löve2D is great. I was getting bored of JAVA for various reasons : the JRE takes too much place, the Sound and Music base libraries are super convoluted, also broadly wanted to change because my pages keep getting quarantined, and it turns out I realised, after testing the very base functions of Love and also noticing that drawing images (so essentially bullets) with an angle was easier, that it was also possible to share a browser version of a game made with Love that would likely get people less nervous to try than my downloadable versions of quarantined games.
The game was balanced on Normal but I had some time to try a bit on Hard and, while it's far beyond my skill level to fight the gun for long without getting hit, unlike the pink homing bullets the yellow homing bullets gradually decelerate and a single phase of its yellow bullets can be gone through by going back and fourth in both direction until all the bullets reach a null speed.
Synchronisation with sound effects was definitely unintended, glad you faced this cool coincidence.
Between a lack of synchronisation between refresh rate and update rate and decimal position of objects you're completely on point about the tickrates, I need to seriously check and fix that.
Thanks a lot for playing and the detailed feedback, I'm very happy you enjoyed the game!