Thanks, I appreciate all feedback!
I didn't actually even think about having a prompt for making sure if the player wants to quit or not. Maybe I'll add it later.
The symbol appearance I'm most likely going to change into arrows. That was what I originally planned, but once you begin hurrying under a time limit, things get overlooked. Also: when you stare at the symbols for long enough and try to code the game while doing so, you get desensitized to how difficult they are to read for somebody else. I've been looking at them for so much that to me they're as easy to read as... well reading letters.
The right side of the screen issue. I rushed the game out for the game jam so I never actually managed to code in symbols coming from the other side as well without breaking the underlying game logic. I'm new to coding, and I pretty much had to learn how to code while building the game, so it's a bit of a mess all around. I'll probably fix that after the jam is done. I don't think I'm allowed to update the game after the submission period has ended.
The multiple cues issue was actually an uninteded coding blurb that I left in to make the middle game a little bit more difficult. I thought it feels kind of bad the way it is, but I left it in anyways due to, you guessed it, lack of time to code the mechanics properly to make the game more difficult!
At that point the game expects you to cherry pick which symbol you want to hit. There is a not very well explained mechanic where you don't take a hit yourself as long as your score, which you can't see, is high enough. You should be fine most of the time even if you let symbols pass, unless the RNG screws you over. Essentially you can let a symbol pass for each symbol you've correctly hit and still be alright. It just makes the transition period to the next scene a bit longer. It's a sort of a buffer for fumbling.
This is the first game I've ever built and since I really haven't coded anythign at all before this, the game ended somewhat crude, short, simple and very amateurish, but I appreciate the feedback all the same.