I was waiting for my Pizza to get done while testing this. So had my earphones off to hear the timer downstairs. Never actually heard what the game sounded like. But even when I do play normally, I tend to have my own music on over things. Then there's the people who enjoy gaming but have some form of hearing loss to consider. Just generally nice to have both a visual and audio cue for things like that.
As for the projectiles, with the current number of projectiles it's fine. But knowing how these games go. You eventually end up with so many things on screen. That anything that can help make projectiles more visible, when in your peripheral vision, is just a nice thing to have. To bring back a TinyRogues comparison. There are some weapons in that game that have a red sprite with a while outline. Almost all enemy attacks in that game have red sprites with a white outline. Which means if you use those weapons, you cannot see enemy attacks. With enough enemies on screen and having enemies = red, projectiles = red. I foresee the exact same issue. Just a sea of red where you don't know what is what. This isn't an issue for everyone though, but usually it feels pretty bad when the source of difficulty becomes visual clarity. Rather than actual mechanical difficulty. Though admittedly a lot of very successful games in the genre, are successful despite horrible visual clarity. Some even have projectile outline as a toggle, since some people genuinely do not want the outline. Others just adhere to very strict color schemes where if something is a certain color. You know for sure it's an enemy projectile. A lot of ways to go about it.